In message , David WE Roberts
writes
This year we haven't turned on the CH yet and I am now wondering what
is going to force our hand.

Below 15C indoors?

Below 10C indoors?

Ice on the inside of the windows in the morning?

In the fairly recent past with new combi boiler we seem to have had the
thermostat set at 20C and the heating on most of the time.
However this year with the mild weather (and back in the house with no
thermostat) we sem to be managing O.K. so far with no heating.

So the thought of turning it on before you actually need it, just to
check that it is working correctly hadn't crossed your mind?

--
geoff