The flame also plays a very important role in this process. Because the flame is conductive, it allows the voltage to pass through its body like a bridge to the burner. This bridge allows the built up spark voltage to bleed off of the igniter tip and move to ground more easily. The resultant ionized flame bridge has now become the path of least resistance for the spark to take across the gap between the spark electrode and the burner body.
By bleeding off the buildup of voltage we stop the spark from occurring. The spark is, in effect, still there, you just canʼt see it.
Possible Causes of Continuous Sparking:
Defective spark wires.
Continuous high heat can cause spark wires to degrade. Use volt/ohm meter to determine continuity of spark wires. Look for obvious cuts/abrasions or pinch points. A defective wire can allow spark voltage to transfer through insulation to ground prior to reaching spark electrode. Under normal circumstances all igniters fire together and if the burner in question has found an easier ground path the spark will go there. It will not, however, in most cases have found a continuous ground path such as what the flame would provide under normal circumstances. This will cause the spark module to re-ignite.
Cracked Ceramic Spark Electrode
Itʼs important to determine whether the spark electrode is faulty. Physical impacts and high heat can cause the ceramic post to fracture or crack. If this occurs the spark can shoot through the ceramic insulation and will normally go to ground on the burner head rather than through the flame
Faulty Burner Grounding
From the spark electrode / burner to earth ground it is important that you have a strong connection. This can be interrupted in many different ways.
1. Soiled spark electrode
2. Soiled burner
3. Soiled burner head
4. Corrosion between the burner head and burner tube.
Normally this will appear as a brownish stain and can be easily cleaned with a small wire brush.
Any of these conditions can interrupt current flow. It is recommended frequent cleaning with a stiff plastic or soft wire bristle brush using pure alcohol or a window cleaning solution that contains alcohol. It is commonly thought that simple igniter cleaning is enough, it is not. You have to clean all three conductive components to ensure good continuity. A small amount of grease or oil can act as an insulator and prevent the spark from flowing properly.
It is common to find one or a series of burners that will only spark occasionally. As with the previously described scenarios check all possible ground faults. This is the number one cause of erratic sparking, not spark modules as is more commonly thought. If you have made certain thatyou have a strong flame current / flame placement / solid ground, replace spark module.