This duct tape or ‘duck tape’ might look metallic, but it’s not. It’s also something you should never use on duct work. Don’t put this stuff on an HVAC system. Instead of the cloth-back ...

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 ...