A.fuel oil supply temperature is normal
B.burner electrode is incorrectly positioned
C.fuel／air ratio is incorrect
D.ignition current is too low

A.when the boiler has been secured long enough for most solids to settle
B.when the boiler has been cooled to ambient temperature
C.only after raising the water level to within 0~5 inch of the high water cutout only
D.after bypassing the low pressure