I'm puzzled by what you are trying to do here. The product you show is a wireless thermostat in the sense that the temperature sensing bit is battery powered, and it sends data to the mains powered bit that you mount by the boiler, which receives the signal and turns the boiler on and off etc. It's designed to be used when you don't have a wire going to where you want a thermostat.
But you do have that wire.
Did you want "wireless" in the sense that you want to use the thermostat from your phone?
If so, the solution is a battery powered 'smart' thermostat.
One example of this (from China!)
or if you just want a better looking digital thermostat with programmer, but not operated remotely:
A Battery Powered Digital Programmable Room Thermostat for controlling either individual or multiple zones of your floor heating system Our Slimline-B V3 battery thermostat offers a viable upgrade route for those with a dial thermostat working on a two wire system. Click Here For: Slimline-B...
www.thefloorheatingwarehouse.co.uk