Brain fade with Drayton SCR on S-plan

[mark2508]

I've been out of the trade for 3 years now and I'm having a brain fade in my old years. I'm installing a Drayton digistat SCR (acually a B.G. WR1 if I'm honest) and wireless drayton stat in to my vaillant 618 system boiler on a S-plan system at home (replacing ancient sunvic wired stat)but for the life of me I can't think of the basics. The diagram for the SCR says to pick up the switched live at the wiring centre and the neutral of the heating motorised valve. Pretty straight forward right? Not for my tattered brain. What switch live? Is it CH On from the timer? Also do I just tee in to the neutral from the motorised valve? I must admit most of my jobs concerning digistats were on Combis. No problem there anyway but the zoned one is leaving me stuck. Cheers in advance

Dear Moderators, I'm not sure if it's okay to say this so please delete this bit if it's not.

As I've retired I've now have a lot of motorised heads and bodies as well as syncron motors, circuit board, pumps, old hot water heat exchangers that can be cleaned up (used on dirty systems before. Old company didn't want to power flush so just used to clean water H/E and put it back. Didn't like to do that but I wasn't the boss. Also a MagnaCleanse system cleaner (the machine not the little the little things you install to keep the system magnatite free). Only used twice. If anyone is interested let me know in a reply post to this. I'm in Southgate, North London.

 

[GuessMan]

The SCR I wired like a room stat.
1 common
3 call

Edited due to fifth beer making me confuse brands.

 

[flameport]

What switch live? Is it CH On from the timer? Also do I just tee in to the neutral from the motorised valve?

Yes and no.

The SCR requires permanent power on L&N.
The other terminals are
common = L from the programmer - only on when the programmer is on.
call = output to the zone valve L, usually the brown wire.
When the programmer and SCR are both on, power is connected to the zone valve, which opens and then switches the boiler on.

 

[mark2508]

Cheers guys. Sorted now. For some reason I was reading the diagram and it looked as if they were saying that the Neutral went in 3 which I couldn't work out and when I followed their instructions it didn't work so I put the "CH on" from the timer in to 1 as the switched live and as you said in the post above, the brown to the motorised valve in to 3 and hey presto! it worked. Of course that wasn't the end of my problems as when I came to pair the SCR with the stat, it wouldn't recognise each other, no flashing red light when I pushed the batteries in (right tray in first of course). Tried for ages with different batteries but in the end I fortunately had a spare wireless stat and that worked first time.
as Homer Simpson would say.