The age of your boiler makes it possibly on the cusp of whether it has the old seal fitted or indeed the new graphite seal. Only a visual inspection of the retaining nuts on the burner would confirm.
The new seals are supplied with nuts that have a 'rubber' locking ring around the inner outside.
As Tony says this should have been serviced at approx 12 months as they do have a tendency for the co2 % to creep up over the year, therefore making the boiler run too powerful and we all know that the Giannoni HE doesn't like too much heat
(French carp 
)
The new seal is supposed to last 5 years as long as it is not disturbed. I for one do not agree with this for various reasons, so my personal policy is to replace at least every 3 years.
The new seals are supplied with nuts that have a 'rubber' locking ring around the inner outside.
As Tony says this should have been serviced at approx 12 months as they do have a tendency for the co2 % to creep up over the year, therefore making the boiler run too powerful and we all know that the Giannoni HE doesn't like too much heat
(French carp )The new seal is supposed to last 5 years as long as it is not disturbed. I for one do not agree with this for various reasons, so my personal policy is to replace at least every 3 years.
