Recirculating direct-fired industrial air heaters shall receive outside ventilation air into the space at a rate determined by what?

The correct choice regarding the determination of the rate at which recirculating direct-fired industrial air heaters shall receive outside ventilation air is based on the requirements listed on the heater's rating plate. The rating plate provides critical information specific to the unit, including operational parameters, safety guidelines, and ventilation requirements. This ensures that the heater operates efficiently and safely within its designed specifications.

Following the rating plate's guidelines is crucial because it considers various factors such as the heater's size, output capacity, and intended application, which may vary among different models and manufacturers. Adhering to these specifications helps prevent operational issues and maintains adherence to safety standards, thus minimizing risks associated with insufficient ventilation or improper installations.

Local building codes, standard industry practices, and manufacturer's instructions do provide useful information and guidelines, but they may not specifically detail the ventilation requirements for a given heater model as comprehensively as the information found on the rating plate. Therefore, referring to the rating plate is essential for ensuring compliance and optimal operation of the heating system.