Here's good thing to do at home in isolation 
Node-RED UI is running on RasPI.
The Boiler controller made of PSU, ESP-12s module, BMP180, OLED display SSD1306, 3 buttons, some connectors, headers, and elecrtonic components.
The firmware based on Homie on top of Arduino-ESP8266 framework.
Features:
- 30A relay overrated enough for any boiler.
- EMI and surge protection.
- OLED display, 3 buttons, and multicolor LED as user interface.
- GUI on Node-RED via hub on Raspberry-Pi. Accessible/visible from mobile phone or computer in LAN or outside of home.
- MQTT reported/controlled.
- Controlled by hardware buttons too.
- Programmable network independent timer. The timer is self-adjusting to season, heating more on winter and less in summer. The adjustment rate is configurable too.
- Enhanced LED signaling:
- LED becomes 'hotter' while water is heating, incrementally changing the color from blue to red.
- (TODO) If the boiler has reached max. temperature and not heating then LED is flashing red meanwhile relay should be on. In this state, the relay is actually off, keeping the electrical wiring of the boiler out of voltage.
- If the boiler is on without timer (manually or via MQTT) the red LED flashes as reminder.
- Flashing blue LED while trying to connect to Wifi.
- Advanced measurement:
- Current reported periodically while boiler is on.
- Energy consumption reported every end of boiler run time.
- Alert about power consumption when relay should be off and there is current: contact slip, hardware problem.
- Air temperature (used for auto-adjustment of timer).
- (TODO) Air pressure (used for auto-adjustment of timer).
Constructive critics how to improve both the project and the documentation are welcome!
Thank you.
