Our heating setup is that we have a combi boiler where you can set the water temperature that runs through the pipes separately for tap and heating, one single thermostat in the hall (right by the front door so it freaks out every time we open it. Thanks, installer) for the whole house, and radiator valves on most but not all of the radiators. We’re a two-storey Victorian red brick semi-detached with a high, open stairwell so a lot of the heat from downstairs rushes straight upstairs.
I have already set the radiator valves to max downstairs and much lower upstairs, as so much downstairs heat comes upstairs and the thermostat is downstairs.
What is the most efficient balance between water temperature and thermostat? I usually set the thermostat at 17-18 degrees C but do whack it up for an hour or so if I’m really feeling cold. Is it better to have the water temperature set high so that the house comes up to temperature quicker (but then the boiler works harder) or to have it set low so the boiler works longer but less hard and the heating stays on for longer?