Smart heating, best options?

[Acuity31]

My current setup is a Logic Combi ESP1 35 which AFAIK has Opentherm capability. The house has 9 radiators and a single ESI ESRTP4+ wired thermostat in the living room.
Correct if I'm wrong but that opens me up to most of the smart systems out there. Ideally I'd like two zone control (upstairs and downstairs) but not sure if that is possible if there is no existing thermostat upstairs currently?
I've watched a few install videos and it doesn't look too difficult, it's more just a case of knowing which system to go with and making sure it all works correctly.
Prefer to avoid any monthly subscriptions however. I've heard good things about Drayton Wiser?

[GasEngineer]

Bear in mind that if you wish to have upstairs controlled separately you will need some pipework alterations to give you two heating circuits.

Easiest would probably be wireless radiator valves.

[FlossyThePig]

I have installed an Evohome system which has smart thermostats on each radiator. This allows me to control each room separately. There are similar systems available.

[B'stard Child]

Acuity31 said:

I've watched a few install videos and it doesn't look too difficult, it's more just a case of knowing which system to go with and making sure it all works correctly.
Prefer to avoid any monthly subscriptions however. I've heard good things about Drayton Wiser?

Lots of things to consider here that you may not have thought about

If you spit the CH circuit into 2 parts (Up and down)

When you run a single circuit (either just down or just up) you will have reduced the avaliable flow (heat capacity) by ~50%

If your boiler has an external pump not managed by the boiler, you are running conventional TRV's and have balanced the circuit via the lockshield. The pump pressure and consequently flow through the rads that are in use will be much faster - leading to hotter return to the boiler and shorter burn cycle lengths

The area not being heated (up or down) will be stealing heat from the circuit that is running leading to the rads on the running circuit having to work harder to maintain room temps

All of the above might not make your boiler happy and the key to efficiency is a happy boiler

I went down the wiser route - Hub, Roomstat and 13 "Smart" TRV's with a boiler that was grossly oversized for my house heat loss and it was fairly successful in managing room temps and schedules but I had to be very careful to not shrink the circuit

I've since replaced the boiler with one that is matched to my house heat loss and gone down the weather compensated flow temps route - as a result I've no "Smart" TRV's gone back to "dumb" TRV's and just one room stat

[Acuity31]

B'stard Child said:

Lots of things to consider here that you may not have thought about

If you spit the CH circuit into 2 parts (Up and down)

When you run a single circuit (either just down or just up) you will have reduced the avaliable flow (heat capacity) by ~50%

If your boiler has an external pump not managed by the boiler, you are running conventional TRV's and have balanced the circuit via the lockshield. The pump pressure and consequently flow through the rads that are in use will be much faster - leading to hotter return to the boiler and shorter burn cycle lengths

The area not being heated (up or down) will be stealing heat from the circuit that is running leading to the rads on the running circuit having to work harder to maintain room temps

All of the above might not make your boiler happy and the key to efficiency is a happy boiler

I went down the wiser route - Hub, Roomstat and 13 "Smart" TRV's with a boiler that was grossly oversized for my house heat loss and it was fairly successful in managing room temps and schedules but I had to be very careful to not shrink the circuit

I've since replaced the boiler with one that is matched to my house heat loss and gone down the weather compensated flow temps route - as a result I've no "Smart" TRV's gone back to "dumb" TRV's and just one room stat

I read that most combi boilers are grossly oversized for most houses because they will always prioritize rapid hot water availability.
I've done a bit of digging and my boilers lowest power output is 7kw, which is around about 4-5 average sized radiators. So trying to use smart TRV's to only heat 1-2 rooms just isn't going to work. It will be constantly cycling on/off which adds wear and isn't efficient.
So having had a rethink, i'll stick with one heating zone and maybe add 1-2 smart TRV's at some point but maybe not.
Also I'm getting mixed opinions on whether I should use Opentherm or not. Some say Logic boilers don't implement Opentherm very well and will keep cycling on/off, others say Opentherm is the most efficient method and you should always use it if your boiler has it.
Ultimately I'd be happy with the ability to turn heating on/off remotely, adjust temps, gather data on energy used and perhaps adjust individual temps for a couple of rooms. Most seem to be able to do all of this but some require a subscription. Drayton seems the best bang for buck and a straightforward install for most boilers.