When must makeup air systems operate with the exhaust system?

Makeup air systems are designed to replenish the air that is removed from a space by exhaust systems. It is essential for these systems to operate simultaneously with the exhaust system to maintain proper indoor air balance and ensure that negative pressure does not occur. When the exhaust system is active, it creates a demand for fresh air to replace the exhausted air; therefore, the makeup air system must operate at the same time to provide the necessary volume of air. This operation helps prevent issues such as backdrafting of gases from combustion appliances, interference with HVAC performance, or unsafe work environments.

If makeup air systems were to operate independently or at different times than the exhaust systems, it could lead to a significant imbalance, affecting air quality and safety within the building. Therefore, simultaneous operation is essential for maintaining compliance with air quality standards and ensuring efficient ventilation.