The objective was to create a remote control interface for the EcoSmart electric tankless water heater. The remote they manufactured had been discontinued and there was no documentation available on the interface protocol.
I was able to reverse engineer the TTL protocol control and status bits using an IR library and determined which were for system on/off, Fahrenheit/Celsius, and water flow detected on/off. I implemented the protocol transceiver as a new class of that library and wrapped it in some code to connect the ESP8266 NodeMCU device to the home automation system’s MQTT broker.
This was a component of a larger project to refit the domestic hot water system in my house.
Project link: https://github.com/PhilRW/ecosmart-remote