Ed Sirett wrote in
:

I really don't want a new boiler!

I'm familiar with some of the other specific models in this series.
The heat input is adjustable over a continuously variable range by
adjusting the burner pressure.
You will need the instructions to find out where the test point is.
The regulator itself is likely to be a screw slot that is accessible
after you have undone a dust cover.

Whilst you could set the burner anywhere within the permitted range
the rating plate shows 3 specific values so that you can record the
'correct' setting for others in the future.

I would guess this boiler has already seen its best years.

WHAT!! It was put in in 97 and cost 2and a half grand!!

However, thanks to all; your comments appear to make sense against the
manual, which is very quiet about it but does have pictures which tie in
with your comments, but calls it a governor.

I also noticed "lint filters" which are probably 5 years overdue for
cleaning - my hovel's a right dust trap, so I'll have a go at it when I can
work out how to get the front off. Can't be harder than me Mums.

Thanx again

Mike R