Which type of igniter is commonly used in older gas furnaces?

In older gas furnaces, the standing pilot is a common type of igniter. This system involves a small flame that is constantly burning, which serves as a source of ignition for the main burners when heat is needed. The standing pilot remains lit even when the furnace is not in operation.

This method was widely used before the advent of more modern ignition systems and is characterized by its simple design and reliability over the years. It requires a continuous supply of gas to maintain the pilot flame, which some may argue could lead to higher energy costs compared to newer ignition technologies that only use gas when necessary.

In contrast, hot surface igniters and direct spark igniters represent more recent advancements in furnace technology, designed to improve efficiency and reduce energy consumption. Electronic ignition systems also fall into the newer category, which eliminate the need for a continuous pilot light. While these modern systems provide various benefits, their complexity and requirements differ significantly from the straightforward and traditional operation of standing pilot systems.