ESP32 Wi-Fi OpenTherm Thermostat
  • 2/11/2021
  • OpenTherm, Wi-Fi, Thermostat

ESP32 Wi-Fi OpenTherm Thermostat

This article describes how to build simple OpenTherm Wi-Fi thermostat using ESP32 WebServer and ESP8266/ESP32 Thermostat Shield. So you can replace traditional room thermostat and control and monitor your boiler remotely via Wi-Fi using web browser on smartphone or personal computer.


  • Enable/disable central heating
  • Enable/disable domestic hot water
  • Enable/disable cooling
  • Monitor boiler fault and diagnostic state
  • Monitor central heating temperature and relative boiler modulation level
  • Set and monitor room temperature

Arduino IDE libraries installation

In case you forgot, or don't know how to install Arduino libraries click here.

ESP32 OpenTherm Wi-Fi Thermostat Sketch

  • Download sketch from DIYLESS github repository esp32-wifi-thermostat.
  • Paste your auth token, specify WI-FI SSID, WI-FI password and update pins configuration according to which module you want to use ESP8266 or ESP32.
  • Connect WeMos D1 Mini or WeMos D1 Mini ESP32 module and upload updated sketch.

Put all things together

Master OpenTherm Shield Connection ESP32 OpenTherm Thermostat Shield

ESP32 Wi-Fi OpenTherm Thermostat Output

Wi-Fi Thermostat Web Server in action

ESP32 Wi-Fi OpenTherm Thermostat Web Server