ive broke the sequence down into segments which i listed below but that all only takes a second or 2.
can you hear the fan run or anything? or does it just fault instantly?
if i was there i would have front cover off,
when either ch or dhw is demanded i would be looking for the pin to rise and make the microswitch on the divertor assembly. (its the top one not the one facing you) that tells the boiler the pump is running.
ok?, i would be listening for fan starting
then listening for ignition clicking.
and would diagnose from there
iain
May 2008