Graham Moore
Any Worcester oil boiler will only run on kerosene , not diesel , if you lift the top of the boiler there will be a white sticker approximately 6 inches by 4 inches , this will have the nozzle sizes for your burner , if its not on the top it will be on the inside behind the front cover , this will also give the necessary pump pressure for the required nozzle , you should call an experienced Worcester oftec engineer , properly set up oil boilers will run much cleaner and more efficient and last longer