Mechanical makeup air for commercial kitchen exhaust systems must be controlled to operate in what manner?

The correct answer is that mechanical makeup air for commercial kitchen exhaust systems must operate simultaneously with the exhaust system. This is essential for maintaining a proper balance of air pressure within the kitchen environment. When the exhaust system is in operation, it removes hot air, smoke, and odors, which can lead to negative pressure in the kitchen. If makeup air does not operate simultaneously to replace the expelled air, it can create an unsafe working environment by allowing harmful gases to accumulate and lead to potential backdrafting of combustion appliances.

Additionally, having the makeup air system operate concurrently with the exhaust ensures adequate airflow, which supports ventilation and helps keep the kitchen cooled and comfortable for staff while removing contaminants efficiently. This simultaneous operation is especially crucial in commercial settings where cooking processes generate significant heat and pollutants, thus ensuring both safety and compliance with relevant codes and standards.