What is the preferred spark gap size for a spark igniter?

The preferred spark gap size for a spark igniter is commonly set at 1/8". This size effectively balances the need for generating a spark strong enough to ignite the gas while also preventing excessive current draw that larger gaps could cause. A tighter gap allows for consistent spark generation under various operating conditions, which is crucial for reliable ignition in heating systems.

Using a gap that is too small may not produce a spark strong enough to ignite the fuel, while a larger gap can lead to weaker ignition and higher energy consumption. Therefore, 1/8" is optimal for ensuring reliable operation and efficient performance in igniting the fuel in appliances like furnaces or water heaters.