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 🙂