Spark Igniter - A.O. Smith BTH 120 Service Handbook

SPARK IGNITER

The water heaters covered in this Service Handbook use a Spark Igniter. The Spark Igniter has two rods: the
sparking rod that has ceramic insulation and the grounding rod, see Figure below. During trial for ignition,
the Control System powers a high voltage transformer (Ignition Control) from J6, and the Ignition Control
supplies high voltage to the sparking rod via the ignition cable. The high voltage potential across the gap
between the sparking rod and the grounding rod generate a spark.
Spark Igniter (1/8"
Spark Gap)
44
BTH 120 - 250 Models
Servicing should only be performed by a Qualified Service Technician
Spark Igniter
(5/16" Gap from
Burner)
Flame Sensor
(1/2" Gap from
Burner)