Hi @pfeifer,
Yes, you’d need a separate temp sensor (as the one embedded with the vent is affected by the airflow).
My smartapp, called ScheduleTstatZones, can create the physical zones (using the vents) inside your home according to the schedules that you configure.
In the mornings, you may want to direct more heat/cool airflow at your downstairs/upstairs rooms;during the day, it may be only downstairs; and at night, only upstairs.
This is what my ScheduleTstatZones smartapp does right now. It’s compatible with any thermostat, any motion/temp sensors connected to SmartThings, And, it does much more than just controlling the vents, it is also able to average out the temperature in your occupied rooms and ajusts the setpoints accordingly (just like the ecobee3 thermostat with its remote sensors, but with any connected temp sensors).
They are also more optional features that you may need or not depending on your requirements: for example,it can control your fan settings or adjusts the thermostat mode.depending on an outdoor temperature threshold.
If you want more details, refer to the community wiki:
http://thingsthataresmart.wiki/index.php?title=ScheduleTstatZones
The smartapp was developed over a long period of time (almost a year now). It’s now fully operational.
See this thread for the long beta testing leading to the final product.
I have several conributors who are using right now, and they seem pretty happy with it.
Regards.