Smart Heater Controller: Retrofitting a heater with an ESP32

I wanted to control my heater remotely and on a schedule, without replacing it. So I put a servo on the heater's control knob and drove it with an ESP32 and a temperature sensor.

The controller follows a weekly schedule and works as a simple thermostat, keeping the room above a minimum temperature. Mode, schedule and temperature can be changed from a small web page on my phone, from anywhere, and the ESP32 turns the heater down on its own if it loses the connection.

To hold the servo in place I designed a 3D-printed bracket that sits over the thermostat, with a cap that grips the dial.