Robertshaw 41-405 Hot Surface Ignitor

The Robertshaw 41-405 Hot Surface Ignitor is a high-performance silicon carbide furnace igniter built for rugged reliability in demanding residential and commercial HVACR applications. Engineered with high-purity recrystallized silicon carbide, this unit, also recognized as the Norton 271D, provides exceptional thermal strength and stable electrical resistance over its service life. As a veteran-grade HVAC replacement part, it is the direct replacement for S1-025-27774-700 and Lennox 98P77, ensuring seamless mechanical fitment and electrical compatibility without the need for field modifications. This 120V AC component utilizes 18-gauge nickel chrome lead wires with high-temperature fiberglass insulation rated for up to 392°F, protecting the connection against the intense cabinet temperatures found in modern furnace and boiler assemblies. Its "Style D" ceramic block ensures a stable mount in gas furnace ignition systems, reaching optimal temperature within 17 seconds for consistent light-offs and reduced ignition delays.

• Universal Compatibility: Serves as a direct replacement for Robertshaw 41-405, York, and Lennox systems, simplifying truck stock.
• Superior Metallurgy: Features embedded nickel chrome leads for maximum conductivity and physical holding strength within the ceramic base.
• Rapid Ignition: Reaches surface temperatures necessary for gas combustion in approximately 17 seconds.
• High-Purity Silicon Carbide: Resists oxidative wear and maintains stable electrical properties across thousands of cycles.
• Industrial Insulation: High-temp fiberglass sleeving prevents short-circuiting and wire degradation from heat exposure.

How do I test the Robertshaw 41-405 for failure?
Perform a Room Temperature Resistance (RTR) test using a multimeter set to Ohms. A functional Robertshaw 41-405 typically reads between 40 and 75 Ohms at room temperature; a reading of "infinite" or significantly higher than 200 Ohms indicates a cracked or burned-out element requiring immediate replacement.

Is handling the silicon carbide tip really a problem?
While modern coatings have improved, veteran technicians recommend handling the ignitor only by the ceramic block. Oils from your skin can create hot spots on the silicon carbide igniter surface, leading to localized stress and premature failure during the rapid heating cycle.

Can I use this 120V ignitor in a 240V system?
Yes, provided the furnace control board or ignition module steps the voltage down. Many 208/240V HVAC units use a 120V output for the ignitor circuit. Always verify the output voltage at the plug with a meter before installing to prevent "over-volting" the element.

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.