viessmann outdoor temperature sensor

[desktop987456]

Hi,
Attached is a basic wiring layout of room stat + programmer working with Viessmann heat only boiler. (pic 1)

I have installed a weather compensation sensor as per schematic (pic2).

When I switch boiler on it shows the display with temperature and CH symbol but it is not igniting.

Is there wiring that I need to change; the room stat clicks, I have put it to 30C but boiler is not firing.

How do I bypass the room stat?
Thanks.

 

[desktop987456]

Can I just put SL from boiler to number 4 on programmer?
1. It should bypass the roomstat;
2. programmer should turn heating on.
3. Weather compensation sensor should work.
Correct?

4. What could be other way if I want room stat to work in conjunction with WC.