I had a nightmare with mine when we moved in, it didn't seem to heat up, we turned it off this summer, but I need to think about turning it on now to make sure it works.
I turned all the thermostats back on today and set them for 21 to test it, but the boiler didn't make a noise so I don't know it it worked or not!! The temp has reached 21 and it has clicked off, so it looks like it works, but I'm not sure if it didn't just heat up to that during the day IYSWIM?
If I hadn't put the heating on, would it have warmed up to 21 during the day anyway? The kitchen read 19 this morning which is usual for September but reached 21 by this afternoon, also usual, so I don't know if the heating did it. The floor didn't feel warm though, but the little flame on the thermostat was on!
I didn't get a manual when I moved in and I don't understand!
Do you know where the controls for the circuits are? Usually in a cupboard or some such. They look a bit like this (that's a big one, probably yours will be smaller).
There you can touch the red pipe and if it feels warm when you are running the heating then the water is going into the circuit. If the cold one feels warm, then the water is circulating through the circuit and returning to the boiler.