I bought a Meross MTS200 smart thermostat to control our gas boiler for the central heating. I then realised that the existing thermostat (Salus RT500) is on low voltage, despite the 3 thick wire feeding it (See picture). I would like to replace it by the smart thermostat Meross MTS 200 that requires line voltage (230V), without having to bring a new wire to the thermostat, which will be a major piece of work (cost, dig in solid wall, repaint, etc...). I wondered if there was something that could be done at the boiler terminal point, to convert the line to line voltage, since main line voltage feeds it the terminal (see picture attached). Thank you for anyone that can help.