Well,
Taking off the old backplate the guy who installed it kindly left the colour coding written in pencil on the wall.
You can just see a bit of it in the right hand cut out in the photo.
Colours/legend exactly met that for the new backplate, so it's all fitted now.
Programing etc. all...
Anybody any idea what colour wires in my existing backplate do what function please, (HW Off/CH Off/HW On/CH On)?
I assume that all I need do is to wire up the new backplate as per existing without the L to 5 link?
Our 20 year programmer has finally given up the ghost, (display missing and CH light on with nothing else functional).
I want to replace this with the Siemens RWB29 but assume I will have to fit the new backplate.
The photo is the current wiring, and the schematic is the wiring for the RWB29...