First of all I do realize this device combo is ultra rare and probably no one has it.
EC-100 is an “energy controller” that talks to a smart utility meter and controls WT-100 thermostat over propietary Zigbee (being the coordinator itself).
From what I understand this product never launched and was discontinued after trials.
Anyway I like the design, so I made this work with HA by implementing a custom MQTT bridge running inside the EC-100 itself. It would translate between MQTT and internal C4 Director, that would control the actual thermostat.
Thermostat alone can join any Zigbee HA network by itself, but it is not usable, because it is using propietary protocol, where APS frames do not contain ZCL, but C4’s custom ascii protocol.
I might make a converter for that, just for fun, later.
PoC: https://www.youtube.com/watch?v=OaH2poMRqtE
Code: GitHub - ArcadeMachinist/c4-ec100-wt100-mqtt-bridge: Control4 SmartEnergy EC-100 Controller and WT-100 thermostat MQTT bridge · GitHub
If you have WT-100 - feel free to reach out with questions and/or help setting up.