Siemens controller Vailant boiler wiring

[Wynn]

I've got a Vaillant VC GB 242 EH boiler and a Siemens RWB9 programmer, I've had problems with my system for a while with the diverter valve motor burning out, when I've checked voltages to the valve they seem to be wrong.

In order to figure this out I've gone through all the wiring again and all is well apart from the connection between the controller and the boiler.

I can't work out from the manufacturers diagrams (below)for these parts how the programmer should be connected to the boiler. it seems that connections 3,4 and 5 from the junction box should go to 3,4 and 5 on the boiler. Is that right, as different manufacturers do they have different wiring conventions.

Untitled

• Wynn
• 1 Nov 2009
• 1

Untitled

• Wynn
• 1 Nov 2009
• 1

I'd be very grateful for any assistance.

Thanks
Wynn

 

[picasso]

connect the wiring centre connection to boiler like this

wiring centre.................boiler

1....................................N

2....................................L

3....................................E

5...................................4

link 1 and 4 in wiring centre, ignore the instructions to connect L N E from 3 4 and 5 to boiler

 

[Wynn]

Thanks for your reply Picasso, but I'm a bit confused by it. you say to connect 1 on the wiring centre to the live on the boiler and 2 to neutral. However the Siemens diagram has 1 as connected to mains neutral and 2 connected to mains mains live. Won't this cause a problem?

Thanks
Wynn

 

[picasso]

your vaillant boiler needs a permanent L N E and a switched live to turn the boiler on, the connections to 1,2 and 3 in the wiring centre are the permanent L N E to the boiler and the connection 5 in the wiring centre to 4 in the boiler is the switched live connection

 

[D_Hailsham]

your vaillant boiler needs a permanent L N E and a switched live to turn the boiler on, the connections to 1,2 and 3 in the wiring centre are the permanent L N E to the boiler and the connection 5 in the wiring centre to 4 in the boiler is the switched live connection

You are quoting the standard Honeywell Y Plan wiring terminal numbers. If you look at the diagram the OP has posted you will see that it shows: Terminal 1 = Neutral; Terminal 2 = Live.

 

[picasso]

my apologies, d hailsham is correct , please connect L to L and N to N wiring centre to boiler. I have edited my previous post to show the correct terminal numbers.

 

[Wynn]

Thanks for helping me out, I'll try it out at the weekend.
Thanks again.

 

[DP]

A word of caution here. Have been there before but I will say it again- If the (red) switch on the boiler is turned off (i.e. the boiler electrics are now isolated by the red switch), timer can apply 240 volts at terminal 4 making part of circuit live. This is the case for two channel programmer that takes 240 volt feed from L terminal internally. A single channel timer/ programmer has no volt contacts that can be used link 3 and 4 to run boiler.

Incidently, VC is a system boiler, not a combi which would be designated VCW