Our quite old, but regularly serviced, Aga has recently sooted up the
complete inside of the lid of the hot (left hand) hotplate. There are
also black soot marks around the ring at the outside of the plate.

The Aga is oil fired.

Any idea what could be causing this? Is it serious, or should a good
service be sufficient to cure it?

On 2007-05-10 00:04:31 +0100, Philip K said:

Our quite old, but regularly serviced, Aga has recently sooted up the
complete inside of the lid of the hot (left hand) hotplate. There are
also black soot marks around the ring at the outside of the plate.

The Aga is oil fired.

Any idea what could be causing this? Is it serious, or should a good
service be sufficient to cure it?

A service will fix it. This is probably some sooting from the burner.

New and excessive sooting suggests incomplete combustion - I'd be
concerned that there might be carbon monoxide too. Has anything
changed recently - could the flue from the stove or air inlets to the
room be partially blocked? Has extra ventilation been added or removed
somewhere else in the house, that could be affecting the air pressure
in the room?

On 10 May, 00:04, Philip K wrote:
Our quite old, but regularly serviced, Aga has recently sooted up the
complete inside of the lid of the hot (left hand) hotplate. There are
also black soot marks around the ring at the outside of the plate.

The Aga is oil fired.

Any idea what could be causing this? Is it serious, or should a good
service be sufficient to cure it?

Favorite is a build up of carbon on the burner leading to poor burn. A
service will solve this.
Other factors - is the flue clear? Birds might have built a nest in it
I take it double glazing or draughtproofing have not been recently
installed?

On Thu, 10 May 2007 00:04:31 +0100, Philip K
wrote:

Our quite old, but regularly serviced, Aga has recently sooted up the
complete inside of the lid of the hot (left hand) hotplate. There are
also black soot marks around the ring at the outside of the plate.

The Aga is oil fired.

Thanks to all who responded (especially those who made the point about
possible safety concerns due to Carbon Monoxide).

In the event, the Aga went out before I could switch it off! We had it
serviced and the technician showed my wife where there had been a
problem with the oil feed pipe at the base of the Aga - the connecting
joint was bad and there had been a leak of fuel. He replaced the worn
part with a new one and it's working fine now.