What is the primary function of make up air in an HVAC system?

The primary function of make-up air in an HVAC system is to compensate for air lost through exhaust. When air is expelled from a building due to processes like ventilation, exhaust fans, or cooking, it creates a negative pressure situation. To balance this, make-up air is introduced from outside to replace the lost air, maintaining a stable indoor environment. This helps to ensure that the system operates efficiently, reducing the chances of drafting and improving overall air quality.

While improving humidity control, increasing air circulation, and enhancing filter life cycle are related aspects of HVAC performance, they do not capture the fundamental purpose of make-up air as effectively as compensating for lost exhaust air does.