To verify proper airflow range for a furnace, which method should a technician use?

To verify the proper airflow range for a furnace, the most effective method is to measure the temperature rise according to the specifications provided on the data plate of the furnace. This measurement allows the technician to assess if the furnace is operating within the designed airflow parameters.

The temperature rise is determined by taking the temperature of the air entering the furnace and the temperature of the air leaving it. The difference in these temperatures should align with the range specified by the manufacturer. If the temperature rise falls within this range, it indicates that the airflow is adequate and the furnace is functioning efficiently.

This method directly correlates the performance of the furnace with the expected heat output, hence verifying not just the airflow but also the overall efficiency and effectiveness of the heating process. A temperature rise outside the designated range could signal issues such as insufficient airflow, which could lead to overheating and potential damage to the furnace or insufficient heating of the space.

While other methods, such as manometer readings, pressure differential tests, and ambient temperature measurements, can provide valuable information about system performance and pressure conditions, they do not directly confirm the airflow as effectively as the temperature rise method related to the furnace's specifications.