White-Rodgers 21V51U-843 HSI Kit

The White-Rodgers 21V51U-843 is a professional-grade Universal 2-Stage Integrated Furnace Control Kit designed for high-efficiency systems utilizing a variable speed ECM blower motor. This comprehensive HSI ignition control solution replaces over 40 existing White-Rodgers models, including the 50V51-XXX and 50V61-XXX series. It features a 16-pin interface for precise ECM motor control and includes a 120V nitride ignitor to upgrade older 80V silicon carbide systems. Contractors can optimize performance via dipswitch selectable settings for heat fan-off delays, cooling fan-on delays, and auto-second stage staging. The board is built with a flash microprocessor and non-volatile memory, providing reliable furnace control board operation under demanding conditions. Technicians can quickly diagnose issues using the tri-color status LED and pushbutton fault history retrieval, ensuring rapid HVAC troubleshooting and minimal downtime on-site.

• Broad Compatibility: Replaces a wide range of OEM controls from Lennox, Goodman, Amana, Trane, and York using included wiring harnesses.
• Advanced Motor Control: Integrated 16-pin output specifically calibrated for variable speed (ECM) circulator motors.
• Field-Proven Reliability: Includes a 21D64-2 nitride ignitor kit for superior durability compared to standard silicon carbide ignitors.
• Efficient Staging: Supports 2-stage gas valve operation with adjustable staging delays to maximize homeowner comfort and fuel efficiency.
• Simplified Diagnostics: Pushbutton retrieval of historical faults and real-time flame current measurement points for accurate furnace repair.

• Does this kit work with 80V ignition systems? Yes, the 21V51U-843 furnace kit includes a 120V nitride ignitor intended to replace the original 80V ignitor in those specific applications.
• How do I configure the motor speeds? Configuration is handled through dipswitch selectable settings on the board; refer to the provided cross-reference guide to match OEM specifications.
• What does the tri-color LED indicate? The LED provides heartbeat status, call for heat/cool confirmation, and specific fault codes (Auto-reset, Lockout, or Pressure Switch errors) for fast ignition control diagnostics.

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.