To measure supply grill air speed, what tool should the technician use?

To measure supply grill air speed, the appropriate tool to use is an anemometer. An anemometer is specifically designed to measure air velocity or airflow in ducts and around vents. It provides accurate readings of how quickly air is moving, which is essential for assessing the performance of HVAC systems and ensuring they are operating efficiently.

In contrast, a thermometer measures temperature, which is not useful for determining air speed. A manometer is used to measure pressure differences in a system, which can be significant for diagnosing issues related to airflow but does not directly measure the speed of the air flowing through a grill. A hygrometer measures humidity levels in the air, which also does not pertain to air speed. Thus, the anemometer is the correct choice when focusing on the measurement of air speed in HVAC applications.