ericmark wrote: ↑Tue Jan 31, 2023 2:40 pm
I realise there is a balance, the higher the temperature the faster it warms up the house, so less warm it time is required, but also the faster you heat up the house, the higher the hysteresis is, and the over shoot wastes energy.
Personally Autumn and Spring temperature set lower than Winter, and most my thermostats (15 in all counting the TRV's) are set as @Razor says with comfort and eco settings, so when a room is required, it is not starting from ambulant temperature, but an elevated level.
The wall thermostat is programmable, unfortunately it does not link to TRV's, but I set the wall thermostat down 0.5 deg for an hour before a room is required, then back up 0.5 deg so boiler will be running as rooms change temperature. This is less of a problem if the boiler modulates.
Most combi boilers modulate, either they must modulate, or have a water store, if the boiler modulates, not sure what the wall thermostat does? OK may seem silly, but if the TRV sets the room temperature, and the boiler will first modulate when return water gets warmer, then start a mark/space ratio to further reduce output, then only reason for a wall thermostat is to turn off boiler on warm days.
It clearly is not quite that cut and dried, but my wall thermostat is mainly there as a programmer, turning the heating on/off at times set, however since it does have a thermostat function, it also removed the need for a frost stat, and turns off heating on warm days.
In real terms there is no answer, as all boilers are not the same, with gas the on/off thermostat is really a relic of the past, today we want to control boilers with the ebus, but the problem is many boilers either don't allow ebus control, or only monitor one room when using it.
The real question is what TRV head? Many wall thermostat will link to TRV heads, and the TRV head is king, that's the bit which does all the work, all the wall thermostat does is relay the massages from the TRV's to the boiler, so down to selecting TRV's then adding a wall thermostat which will work with them.
So looking at cost v functions, if you have 5 bedrooms all going to be used at the same time, you pick the slowest to heat up, put a linked TRV in that room, at maybe £50 and other 4 rooms, a simply programmable type at say £15.
One can set a sequence with even just 10 minutes between them, kitchen, dinning room, then living room, so all heat at first to kitchen so rooms heat up in the order used.
But my house, 2 kitchens, two bathroom, two shower rooms, two living rooms, five bedrooms, plus utility room, hall, landing etc. Having the house heated room by room saves a lot of money, but a two up, two down house will be very different. My last house was open plan, so a single wall thermostat controlled most the house, same with one before that with hot air heating, since air circulating again one wall thermostat did whole house. I have zone valves and in the winter 4 rooms are seldom used. But it is the layout of your house which matters.