Take your time removing the sensor. Parts are plastic. They become brittle over time and can break. Slid out of the duct.

Measuring air flow in an HVAC duct can be a tricky business ... The principle behind the sensor [ItMightBeWorse] is working on is nothing new. He discovered a paper from 2015 that describes ...

Pinwheels are pretty optimized from a design standpoint, and are so cheap and easy to build that putting a pinwheel to work as an HVAC duct flow meter seems like a great idea. Great in theory ...