We recently got balanced ventilation installed, and I have interfaced it with Home Assistant. However — the ventilation unit have three “special modes” that can not be enabled through the Modbus interface; fireplace, kitchen, and override. These can only be set on the touch panel, mobile app, or through inputs terminals on the controller.

So I repurposed an old project and made a three-relay Wi-Fi controlled module, using MQTT to send commands and receive statuses.

Then used Home Assistant to automate it 🙂

I’ve wanted to use an ESP8266 WiFi module in a project for some time now, and after reading about the WeMos board, I figured this was the easiest way to get started. The WeMos D1 mini is quite small and much easier to interact with and program than the ESP8266 devices. So I built this single relay controller, with internal temperature reporting. I am communicating with it using MQTT, which makes it really easy to implement it into things like Home Assistant.

Control three lights or relays, with toggle switches and status LEDs. Uses an AVR ATtiny2313 microcontroller.