New Digital Room Thermostat

[porcupine]

I want to replace the existing old Satchwell room stat with a new digital. The Horstman is a 2 wire set-up according to all I have read but the existing Satchwell is a three wire excluding earth. C/H boiler is an old Gloworm gas floor mounted on a 2 pump system, 1 C/H 1 H/W. Programmer on this is mechanical clock.

Any ideas how I can fit a new digital stat where it only needs 2 wires when the present requires 3????

 

[cross thread]

neutral not required on most digital stats

 

[porcupine]

Thanks. Need only wet my fingers now to see which one left is neutral!!!