Using the heating state change as an automation trigger

[Ceaus]

I'd like to automate an action based on the actual heating status.

Example: When the heater is starting to heat (because it's become too cold), turn on this switch. When the heater has stopped heating (because it's warm enough) turn off this switch.

Looking at the Lovelace card, the thermostat knows when I's heating or not (see orange areas from the screen shot.)

What I'd like to see is that awesome_thermostat exposes a sensor state change which I can use in an automation.

As inspiration, the Plugwise Anna thermostat exposes a binary sensor heating_state for this purpose. See here and here