Fitting External Programmer to Worcester Heatslave Combi

[self builder 123]

Hi

I have a Worcester Heatslave combi boiler which has a built in Worcester twin channel programmer. The LCD display has gone blank, but for now the programmer still works.

I plan to replace the twin channel programmer with a new external programmer.

Looking at the installation instructions for the boiler it shows 4 connections for an external programmer - L, N, SL to CH and SL to DHW. Please see the diagrams Facia Mounted Programmer Connections and External Programmer Connections.

The external programmer I plan to fit is a Siemens RWB29. I have attached a copy of the internal wiring diagram for this programmer.

As I understand it the wiring will be as follows :

The brown wire is L and the blue wire in neutral

The CH On connection ( 4 ) is a Switched Live which will connect to the grey wire at the boiler.

The DHW On connection ( 3 ) is another Switched Live which will connect to the white wire at the boiler.

This makes sense to me. There will be no connections at 1 and 2 on the programmer back plate as these are the OFF positions.

However when I looked at the actual wiring for the existing twin channel worcester programmer I see that there is a 5th ( Orange ) wire ??? Please see diagram Oil Heatslave.

This has me a little confused. Is it something to do with the Pumped or Switched setting on the twin channel programmer ?

Many thanks for any help.

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• self builder 123
• 31 Dec 2010
• 1

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• self builder 123
• 31 Dec 2010
• 1

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• self builder 123
• 31 Dec 2010
• 2

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• self builder 123
• 31 Dec 2010
• 1

 

[Kristoflampie]

Looking at it the boiler terminal strip is only asking for the CH and DHW inputs so I would wire it as you have suggested, the changeover is looked after by boiler thermostats so all its asking for is timed inputs.
I have linked these out before as a temporary fix to get folk back in business and the boiler has worked normally.
Worcester clock is a very straightforward swop tho!!

 

[self builder 123]

Cheers