Retractable ignition system

A retractable ignition system for mounting in a flow passage of a burner having an outlet end, comprising:

• an igniter including a high voltage electrode surrounded by an insulator and extending beyond the insulator to form a tip end of the igniter, the igniter being mounted slidably within the flow passage of the burner, the igniter comprising a ground electrode at least partially surrounding the insulator;
• an actuator connected to a rear portion of the igniter and configured to pneumatically advance and pneumatically retract the igniter with respect to the outlet end;
• and
• a slidable seal between the igniter and the flow passage, the seal being positioned rearward of a gas inlet into the flow passage and frontward of the rear portion of the igniter.

A method of igniting a burner having an outlet face and a flow passage, comprising:

• advancing an igniter located within the flow passage to an advanced position in which a tip end of the igniter is aligned with or frontward of the outlet face of the burner, the igniter including a high voltage electrode surrounded by an insulator and extending beyond the insulator to form the tip end;
• supplying high voltage to the high voltage electrode while the igniter is in the advanced position;
• and
• retracting the igniter in a rearward direction from the advanced position to a retracted position when a retraction condition is met;
• wherein the igniter is not biased toward either the advanced position or the retracted position;
• and
• wherein the retraction condition is one of expiration of a timer and detection of a flame frontward of the outlet face of the burner.