Hi

We have oil rather than gas for our heating and recently have had a new
boiler/burner installed. The old one was 15+ years old and very noisy. Well
this new one worked fine until the last 6-9 months or so when there's been
this loud tapping sound whenever it fires up and heats. When the guy came
over to check it out he'd found that the system had clogged up again
(although the airflow is ok) and after cleeaning out, he had to get a hammer
to the stacks of 'trays' to re-straighten some of them! The system is a
Wall-Mounted Grandee by Heating World.

Any ideas as to what's going on?

Thanks
Justin