Drayton Wiser Smart Radiator Thermostat - £36 @ Amazon

The TRVs are very easy to install. Just unscrew the top off your current TRVs and screw these ones on and follow steps to calibrate them. Takes a couple of minutes per TRV. I'm sure if you asked nicely though they would fit them as part of the thermostat installation.

However, if they are for rads that don't currently have a manual TRV on, that's a lot more time consuming as you will need to drain the system to fit them and also buy extra parts to fit it. I had to do this as a couple of my rads didn't have manual TRVs on. If your rads fall into this category, I doubt it would be included in the installation of the thermostat. (edited)

Same here, I was surprised to find out it can control the boiler without a room thermostat.

I've tested the temperature readings on a room thermometer and the actual Drayton TRV and it's not much different. On average the readings were 0.2 degrees off on the TRV from the actual room temperature on a room thermometer.

As far as I know, you'll need to have a Smart TRV connected on all your operating radiators for this to work properly.

If you have the Smart TRV on just 2 radiators, the boiler would still be pumping hot water through all the other radiators, and only turn off when the two Smart TRVs have reached their desired temperature.

Central heating is cheaper than a electric heater, but the initial outlay for these Smart TRVs is expensive, so it's a long term benefit.

We don't have Smart TRVs, but I do want to get some for all the radiators in the future - hopefully once the prices come down.

Tado have a child lock on them so they can only be controlled from App