Clubman - I've got one in my fusebox. There's a control for both day and night but in the manual I got the day control is more for testing purposes wheras you can modify the night to start taking in heat earlier (-2, -4) or later (+2, +4). Beside both these controls is where the red light comes on to indicate that it has started to take in heat you can also hear a load clicking noise when the red light comes on.
I wonder if mine is different to yours because I'm in an apartment and my night & day meter boxes are in the basement.
The model of my heaters are Creda.