replying to The Natural Philosopher, Mains2Drains wrote:
...... And the reason for the photocell being all tarred up is: A result of
the combustion process failing. All fuels require a Stoicimetric mixture of
Fuel to Air ( circa 1 part fuel to 11 parts air). Failure to correctly set
this results in "incomplete combustion" and a build up of soot/tar deposits.
Setting the correct oil pump pressure (measured oil delivery) and air damper
position (measured air delivery) is paramount for a complete combustion and
clean burn.

Has anyone got the Myson "additional burner data sheet" that's mentioned in
the owners/service manual ?
knowing the manufacturers expected pump pressures would be great to know as
the "industry norms" are ok but not always exact enough for a good clean burn.

--
for full context, visit https://www.homeownershub.com/uk-diy...h-1102783-.htm