For a commercial convection oven, how should I verify the hot-air circulation system?

Check fan placement, duct geometry, heater position, and airflow balance across every baking deck. Before comparing suppliers, fix the product specification, target throughput, and operating condition used for the test. During FAT, use calibrated instruments where relevant and keep the original readings with the acceptance record. The purchase specification should state the method, tolerance, sample quantity, and treatment of nonconforming results. Also confirm cleaning access, routine maintenance points, and the parts that operators must remove between production runs during normal operation.