No idea. Ground Source heat pump and all sorts of clever things going on I don’t understand. No thermostats in the house which is heated with underfloor heating and occasionally a wood burner in one of the rooms. It’s nice and warm and that suits me just fine. I did turn the systems from Summer to Winter a while ago.
When we moved in we had Storage heaters and rubbish insulation, The first winter was so cold we ended up running fan heaters as well. One quarters bill was the same as we pay for a year now and it’s a lot warmer.
I really can’t understand why people sit around in the cold. Surely a hair-shirt warms you up ? 😉