Once upon a time I started developing a simple Opentherm controller on esp8266 for personal use, which resulted in a full-fledged controller product for Home Assistant. I think it’s time to publish it.
The software is free, it develops as I have free time.
The repository contains a board diagram, BOM and Gerber file for self-assembly, but it is also compatible with boards from Ihor Melnik, DIYLESS and others assembled according to this scheme.
Goals and tasks that this software performs:
- Regardless of the “clouds”
- Works autonomously and locally: even if the server is turned off, it will continue to work
- Full integration into HA, without the need to describe mqtt entities
- Hot water temperature control
- Heating temperature control
- Smart heating temperature control modes:
- Equithermic curves - adjusts the temperature based on indoor and outdoor temperatures
- Hysteresis setting (for accurate maintenance of room temperature)
- Ability to connect an external sensors to monitor outdoor and indoor temperature
- Emergency mode. If the Wi-Fi connection is lost or the gateway cannot connect to the MQTT server, the mode will turn on. This mode will automatically maintain the set temperature and prevent your home from freezing. In this mode it is also possible to use equithermal curves (weather-compensated control).
- Automatic error reset (not with all boilers)
- The process of heating the coolant for heating: works/does not work
- The process of heating water for hot water: working/not working
- Display of boiler errors
- Burner status: on/off
- Burner modulation level in percent
- Pressure in the heating system
- Gateway status (depending on errors and connection status)
- Boiler connection status via OpenTherm interface
- The current temperature of the heat carrier (usually the return heat carrier)
- Set coolant temperature (depending on the selected mode)
- Current hot water temperature
- Auto tuning of PID and Equitherm parameters (in development)
- Home Assistant integration via MQTT. The ability to create any automation for the boiler!
I also made a board for installation on a DIN rail. The total cost for self-assembly does not exceed $35. But you can also use other boards.
Repository with additional information here: GitHub - Laxilef/OTGateway: OpenTherm gateway for HomeAssistant
Firmware releases here: Releases · Laxilef/OTGateway · GitHub
I will be glad to see your comments and suggestions.