What @habitat is doing is what a lot of owners with eTRV's would be doing.
This is not like US Thermostats which are attached to HVAC systems. These Thermostats are simply devices that electronically (Z-Wave usually) call for heat when their setpoint is reached or go idle when the setpoint temperature is reached. These Thermostats need something to monitor their operating state and drive a boiler switch, like the "Secure Z-Wave SSR302", based on that state.
@habitat I have posted the app I wrote to drive my boiler here.....
