Danilo Campos' ThermTerm Is a Smart ESP32-Powered Open Source Controller for Heat Pump Systems
Built using off-the-shelf components and a 3D-printed chassis, the ThermTerm is a clever way to automate heat pump operation.
Self-described technologist and "dreamer of optimistic futures" Danilo Campos has put together an open source Espressif ESP32-based controller and home automation terminal for heat pump systems: the ThermTerm.
"I love my heat pumps. They're energy efficient and the fastest way to heat or cool any room," Campos explains. "But I've always hated the remote controls that come with heat pumps. They're clunky and hard to read, especially in low light. In theory, you can program schedules for your heat pumps, but in practice the remotes are too frustrating to use for that. ThermTerm solves all the problems I've had with these physical controls, while integrating the heat pumps into Home Assistant via MQTT."
The compact ThermTerm is based on an Adafruit ESP32-S3 Feather Reverse TFT board with rotary encoder and IR blaster added on. These are housed in a 3D-printed case which exposes three main buttons for mode selection, with a larger 3D-printed wheel connected to the rotary encoder for setting the temperature at a swipe.
"Press the dial to toggle power. Turn the dial to set temperature. Change to heat mode with the bottom bottom, cool mode with the top. Set fan speed by pressing the center button, then turn the dial," Campos says of the ThermTerm's operation. "Through a TFT screen, readouts are visible any time of day. The chunky dial is easy to press without looking."
So far, the ThermTerm sounds a lot like any other thermostat system — until you dig into the details. The build also includes a Sensirion SHTC3 temperature and humidity sensor and a Rohm BH1750 light sensor, giving it local environmental monitoring and simple occupancy detection at night. Instructions are passed on to the actual heat pump system via infrared, meaning there's no awkward wiring, and the device connects to Home Assistant or any other MQTT-compatible home automation platform.
"Out of the box, ThermTerm supports Mitsubishi's infrared protocol, since that's the system I have," Campos writes. "Thanks to integration with IRRemoteESP8266, you can make ThermTerm work with your own heat pumps by writing a few lines of adaptor code. No signal analysis or reverse-engineering required."
Campos has released the project under the permissive MIT license on GitHub, including full source code and 3D-printable files for the enclosure and large rotary encoder knob.