Hot Surface Ignitor
Updated
The hot surface ignitor is the part that lights the burners in most modern gas furnaces, replacing the standing pilot light older furnaces kept burning around the clock. It is a small ceramic or silicon element that glows orange-hot when the furnace calls for heat. Gas flows across it and ignites.
Because it heats and cools with every cycle, the element grows brittle over the years. A hairline crack is enough to stop it working, and even the oil from a bare finger during handling can shorten its life. A furnace that clicks and hums but never produces heat often traces back to this one part.
Common Questions
What is a hot surface ignitor?
The hot surface ignitor is a ceramic or silicon element inside a gas furnace that glows orange-hot to light the burners each heating cycle. It replaced the standing pilot light, which burned gas around the clock whether the furnace was heating or not.
What are the signs of a failed ignitor?
The furnace starts its cycle: you hear the draft fan spin up, but no burners light and no heat arrives, often followed by the system locking itself out. Since a failed ignitor and a dirty flame sensor look similar from the hallway, a furnace repair visit tells them apart.
How is a hot surface ignitor different from a pilot light?
A pilot light burned continuously so a flame was always waiting; a hot surface ignitor only heats up when the furnace actually calls for heat, which wastes no gas between cycles. The flame sensor then confirms the burners lit before the cycle continues.
Related Terms
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