Reznor 121865 Ignitor

When the call for heat fails on a Reznor gas-fired unit, a fouled or cracked Reznor 121865 Ignitor is the primary suspect. This heavy-duty silicon carbide hot surface ignitor is engineered specifically for direct-fired makeup air heaters and commercial HVAC systems, operating at a standard 120V AC. As a technician, you know that consistent combustion depends on the element reaching a precise ignition temperature of up to 1800°F (982°C). This OEM replacement part provides the rapid thermal response necessary to safely light the burner assembly, preventing delayed ignition or nuisance lockouts on the control board.

The Reznor 121865 features a robust 2-wire lead configuration for seamless integration into the existing wiring harness. Its recrystallized silicon carbide construction is designed for high-cycle industrial environments, ensuring dependable furnace ignition even in demanding conditions. When troubleshooting, verify the internal resistance typically falls within the 40-120 ohm range at room temperature. Proper handling is critical—avoid touching the ceramic element with bare hands, as skin oils can cause hot spots and premature failure. This hot surface igniter is the reliable professional choice for restoring peak efficiency to ADF and ADFH model units.

• Precision OEM Compatibility: Specifically designed for Reznor ADF and ADFH model direct-fired makeup air heaters.
• High-Temperature Durability: Engineered with silicon carbide to withstand repeated 1800°F heating cycles.
• Fast Ignition Response: Reaches operational 120V voltage requirements quickly to ensure safe gas-air mixture combustion.
• Simplified Field Replacement: Features a standard 2-wire lead design for fast installation during service calls.
• Commercial Grade Performance: Built to meet the rigorous demands of industrial gas-fired heating systems.

• Why is my Reznor heater clicking but not igniting? This often indicates a cracked 121865 ignitor that can no longer complete the electrical circuit or reach the necessary ignition temperature.
• Can I touch the 121865 element during installation? No. Oils from your skin can cause the hot surface igniter to fail upon its first cycle; always handle by the ceramic base or use gloves.
• How do I test if my Reznor ignitor is bad? Use a multimeter to check for electrical resistance (ohms); a "0" or "OL" reading confirms a broken element that requires immediate replacement.

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Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.