Isn't that the same ( almost ) as having as many zones as there are radiators.
Does the smart valve tell the boiler to fire up when necessary ? If so then how smart and reliable are the communications between the smart valves and the boiler
Not all electronic TRV heads are equal, the EvoHome was one of the first,
and the thermostat was more like a building management system. Drayton Wiser claim to have built in algorithms to speed up temperature changes without over shooting. But there is also the non linked like the terrier i30 and the eQ-3, the latter can be got in a bluetooth version so where there are two radiators in one room they can be linked.
The problem seems to be manual operation, this
Energenie TRV head has very few manual controls, it is a clever head with two sensors one for air and one for water, so compensates for radiator being hot. And on the computer shows both target and current so can use that to set the lock shield valve, it can connect to some wall thermostats, but wrong way around, the wall thermostat sets the TRV, not the TRV setting wall thermostat. So the much cheaper eQ-3 (I paid £15 each for bluetooth version before brexit) with window open detect, and full manual control,
is in many ways better, I walk into room, press the right hand button and it swaps from eco to comfort mode, but does not link to boiler.
With an oil boiler not being linked is a problem, but with a modulating gas boiler the boiler rarely turns off in the winter it just turns down, so may be want one or two linked TRV heads, but most can be stand alone.
Central heating is a compromise, it would cost too much to have a fully automated system with each room exactly right temperature, so we aim for near enough, so I have wall thermostat drop 0.5ºC before the TRV programmed change, then back up 0.5ºC as it changes to ensure boiler runs, but I have oil, with gas not such a problem.
I think EPH make an opentherm thermostat which can be configured as master/slave, so using old fashioned motorised valves to form zones you can still control boiler analogue, but then no TRV link to wall thermostat, so in the main it is either/or, so either motorised valves create zones, or TRV's create zones, well suppose a electronic TRV is a motorised valve.
Speed is important, no good having geofencing with UFH unless you trigger it 200 miles from home. So if the first room to be used is kitchen, then large kick space heaters in the kitchen can heat it up fast, you can arrange a sequence using times, so kitchen, dinning room, living room, and bedroom have a delay between them, but clearly if boiler can modulate to 6 kW then unless radiators which are turned on can deliver 6 kW then boiler will start cycling. So some planning is required.
I have 4 so called bedrooms up stairs, but I call two bedrooms, one the craft room and last one office, using programmable TRV heads I can heat craft room during the day and allow bedrooms to cool, down stairs I have a dinning room, but rarely used, we eat in the living room, so I can allow dinning room to cool. I think we all change what we use rooms for over the years, so we want the flexibility with the heating, the old idea of splitting home upper and lower is simply not flexible enough to allow change of use for rooms.
