Replace BG RS2 thermostat with Honeywell DT90E

[marinmv]

Hi

Can anyone help? I want to replace an old British Gas RS2 thermostat with a digital Honeywell DT90E. Not sure about the wiring, I have 4 wires in the RS2, one of them bare and disconnected. Images below show the RS2 and diagram of the DT90E. Where should the wires go? Boiler is an Ideal Combi +.

Thanks

 

[endecotp]

The "bare disconnected" wire is an earth and seems not to be needed by the new thermostat either, so you can leave it disconnected - but safely put of the way so that it doesn't touch anything.

It looks like the new thermostat doesn't need a neutral connection. Is it battery operated? If that's true, the blue neutral wire can also be left unconnected (and safely out of the way).

The live wire (brown) should be connected to the terminal A, and then the yellow to terminal B. Don't connect anything to C.

 

[marinmv]

Many thanks endecotp, the new thermostat is battery operated.