When must the makeup air system start to operate in relation to the exhaust system?

The makeup air system is designed to replace the air being expelled by an exhaust system, maintaining pressure balance within the building and ensuring proper ventilation. For effective operation and to prevent negative pressure, which can lead to backdrafts or reduced performance of heating and cooling systems, it is essential that the makeup air system starts operating simultaneously with the exhaust system. This coordination ensures that as air is being removed from the space, an equal amount of fresh air is being introduced, thus maintaining air quality and thermal comfort while optimizing the overall efficiency of the ventilation system.

Starting the makeup air system before or after the exhaust system can create an imbalance in air pressure, potentially leading to issues such as exhausted air not being effectively replaced, which could contribute to an unsafe environment.