Hi Guys (& girls)!
I wonder if you can help pls?
I've changed my old sunvic TLX2259 room stat (4 wire) for a shiny new Siemans RDJ10 2 wire and connected as other forum posts have identified (T3 red to LX, T1 yellow to L2) & blanked off the blue neutral & earth (stat end).
...Although...