If it is a Floor Standing Boiler, Remove the front casing panel, by pulling from the top, inside the boiler at the bottom is the Burner unit, on the front of the burner you should see a Red Light glowing, press this button firmly and release, the Burner should then attempt to Start, the Fan will run for about 12 seconds, then the flame should ignite, if all is well, if not the burner will stop and the red light will come on again after a further 5 seconds, you will have to wait about 60 seconds before you can reset again.
DO NOT RESET BURNER MORE THAN TWICE without resolving the fault, as you could be injecting oil into the combustion chamber which could cause a problem later. www.oftec.org will help you to find a Qualified Technician in your area
www.elanar.co.uk, May 2009