I have ducted air conditioning which is great, but I find it pretty wasteful when hot or cold air is pumped into a vacant room. This is a totally solvable problem - I could get builders in to tear out my ceiling, HVAC techs to install dampers, and electricians to wire it in and add switches. Great, right
As an alternative I could just design a 3D printable valve using a servo and a NodeMCU (or any ESP8266). This can then just be put inside the duct, wired in (maybe with PoE), and connected to Homeassistant via HomeKit. So much easier
So I printed and assembled the valve, went to install it, and promptly discovered I’d engineered a square plug for round hole. Or, more accurately a square plug that needs to go through a square hole diagonally. The issue is that I have to navigate an outlet vent to install the valve, and of course I didn’t account for this in the design. So it’s back to the drawing board for what is now version 3