In general, we’ll want to see residential HVAC equipment with air velocities between 300 and 700 feet per minute (depending on the outlet type and location). You can use the Testo Smart Probes app to set up a timed average duct traverse. After you type in the specs of the equipment you’re measuring, you can run the clock and hold the Testo 410i up to the vent you’re measuring from.

In this case, we ran a test for 46 seconds and stopped the test. The 410i picked up 106 CFM and 193 feet per minute (we intentionally kept the velocity that low for noise reduction purposes and had oversized ducts).

Testo: https://www.testo.com/en/