[Covid van de Mic]

If you want to do the absolute cheapest way with off the shelf parts (more off the shelf than an ESP32 board) something like this should work:

https://www.amazon.com/Wireless-Transmitter-Receiver-Universal-Controller/dp/B08CCVJWL9/ref=sr_1_4?crid=12N18CN0WA7XT&keywords=x10+wireless+relay&qid=1641940761&s=electronics&sprefix=x10+wireless+rela%2Celectronics%2C122&sr=1-4

That would be what triggers the non-CAN relay-based Espar to start.

I've got a China-spacher diesel heater so am going the ESP32 route. I'm hoping I can learn the signaling on the wires from the Afterburner community, though the designer mentioned someone started selling knock-off's using his design and code so I may be on my own.