Vaillant VCW GB 242 E :- Failure to iginite when central heating demanded?

anyone know how to clean out the dhw heat exchanger?

Pete C
December 2011

My Vaillant VCW GB 242 E Combi Compact Wall Mounted Boiler is failing to ignite when the central heating is switched on. I can hear the fan starting up but when i look in the combustion chamber there is no fire .
The hot water on demand is working fine.
Boiler Water Pressure around 2bar.
Can anyone provide any ideas as to the cause of this issue?

Khaled
November 2011

I have the same problem except the hw system is now also not working.

I followed gilo's suggestion and took off the front panel. I can see two rocker switches, one black and one red but they are to the bottom left rather than middle mounted on a cast white metal box compete with a small black button (which has no effect when pushed).

With ch set to run, the red switch is on (glowing) and if I toggle the black switch I can hear the pump start/stop but no flame.

Any other ideas?

Will
October 2009

Thanks for your reply.
This seems to be the issue. I have had the CH working now by pressing the black rocker switch back, at least thats a starting point for me.

lancspne
October 2009

new water valve req. remove front panel front middle is a black rocker switch moves on hw demand put ch on pull this switch back off the metal switch ch will fire. usually just scale from a small leak not letting it seat fully.

gilo
September 2009