Core Function & Specifications
Purpose: Detects the presence of a burner flame and signals the control board to shut off the gas valve if the flame is absent or unstable. This prevents unburned gas from accumulating.
Design: 90-degree angle rod with a ceramic insulator for high-temperature durability.
Electrical Specs: Operates on 5–10V, reading an electrical resistance of 3–20 Ohms and outputting 0–5V based on flame strength.
Maintenance & Replacement
Symptom of Failure: A faulty, dirty, or degraded sensor may cause your furnace to ignite but shut off immediately (often referred to as short-cycling or flame drop-out). [1, 2]
DIY Maintenance: Often, a flame sensor doesn't need immediate replacement. It can be restored by gently cleaning the metal rod with a fine-grit abrasive pad (like steel wool or a dollar bill) to remove carbon buildup. [1]
Professional Installation: Because this is a safety-critical component tied to combustion and gas flow, professional installation is heavily recommended.
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