Exchanging room thermostat

[ragsusu]

I want to exchange a Drayton RTS1 room stat with a Drayton Digistat 3 programmable.
The instructions state L on the RTS1 goes to 1 on the Digistat ;
N & Earth are not required on Digistat so presumably I will isolate them ;
3 on RTS1 connects to 3 on Digistat (Demand or call for heat) ;
That leaves a connection to 2 on the Digistat (Satisfied) -Where do I get that connection from?
Can anyone assist please?

[ianmunt]

Find it hard to understand that neither neutral nor earth required.Presumably it is isolated in someway meaning there is nothing to earth,but how does ie obtain power to run? Is it battery powered>To function as a stat it switches a circuit,so there has to be an in and an out connection.Are you sure that the wire you are assuming to be neutral isn't the switched live lead?
Think you might be out of your depth on this one and should seek advise locally.
Sorry not to be more helpfull

[ragsusu]

Thanks for your help. I think I'd better contact Drayton & get their advice.
Thanks again