your fan inside the combi might be knackered try turning it on and listening in the top right hand corner to see if fans working ... in which case might need replacing or could be the air pressure switch is knackered ...
plummed out
February 2010
I can answer this question...
my worcester 24cdi has stopped working after i left it on all night. ?
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix home heating systems.