White-Rodgers 21V51U-843

White-Rodgers 21V51U-843 is a universal two-stage hot surface ignition (H.S.I.) ECM circulator furnace control replacement kit. It combines two-stage ignition with variable-speed ECM control to support modern furnace performance. This kit replaces all WR 50V51-XXX'S and 50V61-XXX'S two-stage H.S.I. systems with 80v Or 120v Ignitors, offering broad compatibility for legacy equipment. Designed as a single replacement solution, it covers multiple older control families while preserving proper ignition sequencing and burner operation.

The universal design provides a single replacement solution that covers multiple older control families while ensuring proper ignition sequencing and burner operation across a variety of configurations.

• Replaces WR 50V51-XXX'S and 50V61-XXX'S Two-Stage H.S.I. Systems
• Supports 80v Or 120v Ignitors
• Universal Two-Stage Hot Surface Ignition Control
• ECM Variable-Speed Circulator Furnace Control

Compatible with WR-based two-stage H.S.I. and ECM circulator setups, the 21V51U-843 consolidates essential control functions into one versatile kit for use with 80v Or 120v Ignitors.