Smart radiator valves

NannaH

If you haven’t got a wifi ‘hub’  connected to your boiler that is controlled by an app or smart thermostat controller then smart trvs by themselves will just be expensive ornaments - they have to be paired with the system. 
Hive mini ( app controlled)  is £80,  hive trvs are around £50 EACH.    Fitting the hive or similar set up will be £75 ish (  that’s what my husband charges)  if whoever wires it up needs to go into the boiler , which they should to check the wiring)  they need to be gas safe registered as well as electrically qualified.  

KennyScout

It’s pretty simple to install the system (e.g Tado), if you’ve already got TRVs and a thermostat. The tado room thermostat acts as the boiler control (and it’s case of 2 wires from your old thermostat to the new one following a YouTube video), and try the hub let’s the TRVs control the boiler via the thermostat. Set up costs are high depending on how many rads you have but you can significantly reduce costs by only heating spaces you’re using. For me it an easy choice. 

Kiran

I've had the Honeywell Evohome for 3-4 years, it is expensive but in a large house it has saved a lot of money on oil. It would need a new control installed as the TRVs need to be able to demand heat. I have a bit of a hybrid setup, habitable rooms have smart TRVs and circulation areas have standard TRVs. Bathrooms have uncontrolled rad valves to act as a bypass. Basically when one of the habitable areas demand heat the areas with standard TRV's are supplied too until that area reaches its desired temperature and then shuts off. This setup saves on the more expensive smart TRVs and means you aren't demanding heat for a hallway or utility etc.