when igniting, not all the burners light, sometimes just the one by the spark, sometimes just the right hand burners) it cuts out and restarts the same .. then WOOOOF all the burners light and the damn thing almost blows off the wall!!!
Heat, flows etc are fine .. recent new diverter ( not related)and gas valve fitted( didnt resolve)
can any body help with diagnosis??
thanks

Steven Powell, April 2008

hi i have a vaillant 828 comi boiler. the boiler has spoted working. the green light stays on and no sigh of the fan working. dianostics say is the fan or the air presure switch or curcit board. i have change the air presure switch no difrence still not working. I checked if the fan is getting power very strange the brown live switch connected to the fan is live when tested but then cliped into the fan no live power . this realy confused me how can one wire have power then not? i reset the boiler many of times and once or twice the fan has worked them stopped. the fan seems ok but could some on please help me.

M.Sohail, May 2011