Interesting, I thought Hive was considered as 'Smart' however I suppose it is down to what one considered as being 'Smart'.
My Nest called itself 'Smart' it would use the alterations you made to the heating system to build up a sequence, and also looked at internet weather reports to decide what setting to use, it had geofencing, and would I am sure work well with any hot air system, but not really designed for the UK hydraulic system.
So we start at the boiler, as one is unlikely to change that in a hurry, OpenTherm I am sure works well, but little point even talking about it if the boiler is not OpenTherm enabled. There are some other ebus controls, but some times they will not work with TRV heads, so then looking at design of the house.
The TRV in most homes is king, it can control every room independently, and it can control the boiler in two main ways, the return water temperature, and with wireless link to a hub.
I inherited Energenie TRV heads, but the Energenie wall thermostat has to be hard wired, and I had only two wired main house to the flat under house where the oil boiler was, and there was no wiring for a tank thermostat, I thought Nest would work with Energenie I was wrong, but Nest only needs two wires between thermostat and hub, so seems a good way to get around the problem of only two wires.
I have since fitted Wiser as well, yes relies on two batteries, but since one of two thermostats not left with nothing if batteries go flat.
All my TRV heads also use a pair of AA batteries, but if the go flat only affects one room. There are wireless DHW tank thermostats, however I can't turn DHW off, and still have central heating (C Plan) and in summer cheaper to use electric. At least for the amount we use.
I did look at mothers Worcester Bosch boiler, with the idea of fitting a thermostat to the ebus, but the thermostats at the time, did not connect to the TRV heads, it is all well and good saying XYZ system is the best, but in the main they cost an arm and a leg, so we settle for some thing half way.
If you have three bedrooms, likely want them all to switch on at same time, so only one TRV needs to be linked.
Tried geofencing and it left me in the cold, high winds took out the EE mast so my heating thought I was not home. And the house heats too show, so what are your aims?
