There is a controller app that goes with the driver for each thermostat. It syncs the temp to the thermostats, and it subscribes to the operating state of the virtual thermostats to run the relays.
The virtual thermostat doesn't need to know if the valve is on or off, that is all on the controller to react to the driver's operating state. My controller also does the syncing for temp from the sensors, and the sync between the thermostats, and it even uses the temperature offset of the T6 to force it to read the rounded value of the Zigbee temp sensors on the T6 screen. It is very handy that the community T6 driver has a temp offset command, and attribute, so I can change the temp on the thermostat using the offset, and get the current offset value back.
Actually, I did a post on it at the time. Current code is not using slope calculations or any of that more complex stuff I tried. I now just use outside temp to adjust the cycle time by a coefficient in the settings, set for each area.
