Our thermostat uses about 2 watts, which includes the Wi-Fi connection. That is too much for batteries and you would have to change them frequently. That is why we supply a central heating boiler interface to power the ThermoSmart.
You must place this boiler interface between the 2-wire connection that runs from your boiler to your thermostat. Preferably close to your central heating boiler, but it can be placed elsewhere. Do NOT place the boiler interface IN the central heating boiler. That increases the risk of interference. The boiler interface is powered using an adaptor.
You therefore need a power socket near the boiler interface, not next to the thermostat. If the current wiring to your thermostat has 2 or more wires, you can use it for ThermoSmart