Furnaces can have different types of ignitors depending on their design and technology. The most common types of ignitors found in modern furnaces are:
1. Silicon Carbide Ignitor: This type of ignitor is made of a ceramic base and a heating element composed of silicon carbide. When an electrical current is applied to the ignitor, it becomes hot and glows, igniting the gas released by the furnace's gas valve. Silicon carbide ignitors were commonly used in older furnaces.
2. Hot Surface Ignitor (HSI): Hot surface ignitors are widely used in modern furnaces. They are made of a durable material, such as silicon nitride or silicon carbide, that glows hot when an electric current passes through it. Unlike the silicon carbide ignitors, HSIs do not rely on the spark to ignite the gas. Instead, they heat up and transfer heat directly to the gas, initiating combustion.
Hot surface ignitors are preferred over silicon carbide ignitors because they are more reliable, have a longer lifespan, and are less prone to failure. However, the specific type of ignitor used in a furnace can vary depending on the furnace's make and model. It's always advisable to consult the furnace's manufacturer or refer to the furnace's documentation for accurate information about the type of ignitor it uses.