cylinder stat wiring

[richard hayden]

Im replacing my cylinder stat but am unsure of connections . Existing stat has 2 connections ...one goes to programmer & other goes to hot water motorised valve . New stat has 3 terminals ....I assume common connects to programmer as the feed ,but does the motorised valve lead go to the call for heat or the satisfied terminal ??
Help much appreciated

 

[Puddle]

call for heat ........to cylinder