Airflow can be one of the most challenging measurements a high-performance HVAC contractor must take. The Fieldpiece® STA2 Hot-Wire Anemometer is an affordable test instrument that offers an accurate and simple way to assist with this challenge.

Fieldpiece STA2 In-Duct Hot-Wire Anemometer

The instrument measures velocity, temperature, and airflow quickly inside a duct system so you can tell how much air is moving through a duct.

The STA2 has a backlit dual display allowing you to measure velocity in fpm (feet per minute). It calculates airflow in cfm (cubic feet per minute) with the duct dimensions entered on the display. The instrument also displays the dry bulb (db) temperature in the duct.

The Fieldpiece STA2 includes:

  • STA2 Hot-Wire Anemometer and a 9V battery
  • Replaceable probe with protective shroud
  • Magnetic rubber boot with hanging strap.

The most common use for this instrument is in a duct traverse. You take a series of readings with the anemometer probe in a grid pattern inside the duct to determine average velocity and airflow.

The STA2 offers timed or point-by-point traverse options. Personally, I prefer a point-by-point traverse for simplicity and so I can see the different air speeds in a duct.

This anemometer is a great way to verify fan airflow when a blower wheel is dirty, and you need an accurate measurement. You can also use it to check the air speed moving across registers and grilles when customers complain of noise.

In addition, it also helps you discover excessive turbulence inside a duct system. You can verify the face velocity of air filters to assure they operate in an acceptable range to capture particulate.

If you’re interested in learning more about the Fieldpiece STA2, go to the National Comfort Institute store at

— by David Richardson, Director of Technical Curriculum