There is also the UK Genius Hub (aka Heat Genius) system. I have this working well on our 20 year old boiler. Needs a heating engineer to replace the wired in control to the boiler (part of the £100 installation for in my case).
An excellent recent integration by @cumpstey in this thread works perfectly for me, allowing me to add the Thermostatic Radiator Valve to each Room in SmartThings. The system uses Z-Wave, though you have to link everything to the Genius Hub.