White-Rodgers 21M51U-843 Ignition Furnace Control Kit

White-Rodgers 21M51U-843 Ignition Furnace Control Kit is a universal, 2-stage, 3-speed control module designed for furnaces. It supports multiple fuel types including natural gas, manufactured gas, mixed fuels, LPG, and liquid propane, delivering reliable ignition across a range of setups.

This kit features integrated flame sense, hot surface ignition, and a four-trial ignition sequence with a 3-second ignition trial time. It provides a safe 15-second prepurge and a rapid flame failure response within 2 seconds, ensuring dependable operation and protection for your furnace system.

• Voltage and power: 120V AC input, 4 Amp valve rating at 132V AC
• Size and temp: compact 5.25" W x 1.25" D x 8" H, operating -40 to 175°F
• Relays and control: gas valve relay 1.5A @24V AC; inducer 120V AC 2.2–3.5 A; circulator 120V AC 14.5–25 LRA/FLA
• Loads and humidity: humidifier and electronic air cleaner loads 1A @120V; humidity range 5–93% RH
• Compatibility: universal furnace compatibility with 50M51-843 ignition control module and 21D64-2 hot rod universal igniter kit

Designed for easy installation in furnace applications, the kit combines reliable ignition control with a robust flame sensing system for consistent heat, safety, and performance.