I am having a problem with boiler. Loud banging noise from inside casing. with front removed, there is seen a blue flash from beneath the air gas mixer unit.(Item no 29 on user handbook diagram) How can this be rectified and do i need an engineer/installer? 
I would not recommend a worcester bosch boiler again, had a new fan and timer unit fitted so far.
I would not recommend a worcester bosch boiler again, had a new fan and timer unit fitted so far.
