How does Better Thermostat control my main themrostat?

[dgibbs64]

I have setup all my TRV's in each room and are working fine. However, I was wondering how all the rooms co-ordinate with my main thermostat that controls if the heating is turned on? For example, if I all rooms are at 18C, and I increase 1 room to 21C, then my heating does not turn on to heat up that 1 room. Do I have to set up an automation? It is not clear from the docs how this works.

Thank you

[reinhardsiegel79]

I use this integration on top of better thermostat for exactly this use case: https://github.com/nielsfaber/zoned-heating