wiring Drayton thermostat

[shiri.masoud]

Hi, Im trying to change my current old thermostat with Drayton RTS1, could you please guide me with right wiring (with colors please).
thanks in advance

 

[RandomGrinch]

Could you confirm that there is only a brown and a blue wire connected directly to your existing stat?
It appears as if there is an additional blue wire linking terminals 1 and 4?

 

[shiri.masoud]

many thanks, my problem is solved know and boiler gets on/off correctly