Which Thermostat should i choose?

[carlosg]

I have an old Valliant Combi VCW Sine 18 T3 boiler and would like to change the old mechanical room thermostat. The manual states the stat model is a vrt378.
I would love to upgrade to a modern digital stat if possible.
I have checked the wiring of the old stat and there are 3 wires - yellow, red & blue. There is no earth wire that i can see so am really stuck as to what is a direct replacement. anyone any ideas?

 

[GeckoGas-com]

I cannot recall or find any vrt378... I'm presuming this is just an obsolete stat.

However; any zero-volt switching room stat will work... So my question has to be do you want wired or wireless?

 

[carlosg]

Hi - Thanks for the prompt reply. Although the manual states a VRT378 i have rechecked the stat and it has sunvic tlx 2259 written on the inside.
What would be the best replacement for this?
I previously tried a replacement stat from my local diy store and had to return it as it clearly stated that it must be earthed and the old stat doesn't have any earth wire to connect.