What do prerotation vanes control in an HVAC system?

Prerotation vanes are designed to control the airflow direction within an HVAC system. By adjusting the angle of the vanes, the system can manipulate how air enters and circulates through the system. This control is crucial for optimizing efficiency and ensuring proper distribution of conditioned air.

While capacity and temperature are important aspects of HVAC systems, prerotation vanes specifically function to manage airflow dynamics rather than directly influencing those parameters. Pressure levels may be affected indirectly by airflow changes, but prerotation vanes are primarily focused on directing the flow of air to maximize system performance and maintain comfort levels in conditioned spaces. Thus, the correct answer accurately reflects the primary function of prerotation vanes in controlling the direction of airflow within the system.