Lennox 74W72 Gas Manifold

The White Rodgers 50A55-843 is a universal integrated furnace control board designed to streamline service calls by replacing a vast range of silicon carbide ignition modules from White-Rodgers and various OEMs like Carrier, Goodman, Lennox, and Trane. This hot surface ignition (HSI) controller utilizes a microprocessor to provide constant monitoring of the gas burner, inducer motor, and fan cycles. It features a replaceable 5-amp automotive-style fuse to protect the 24V transformer from shorts, and diagnostic LED indicators that simplify troubleshooting by displaying fault codes for system lockouts or component failures. For contractors handling Trane units, the 50A55-843 includes a specialized jumper wire for RO1 to RO2 terminals. With adjustable fan delay settings via dip switches (60 to 180 seconds for heat) and dedicated 120V terminals for humidifiers and electronic air cleaners, this board offers the flexibility needed for high-performance HVAC furnace maintenance and reliable system restoration.

Key Benefits

• Broad Compatibility: Functions as a universal replacement for the 50A50 and 50A55 series, reducing the need to stock multiple OEM-specific boards.
• Enhanced Diagnostics: Integrated flash code diagnostics provide immediate visual feedback for troubleshooting pressure switches, rollout limits, and flame sensing issues.
• System Protection: Includes a replaceable 5A fuse to safeguard the low voltage transformer and control circuit against wiring errors.
• Flexible Configuration: On-board dip switches allow for precise blower off-delay adjustments to maximize heat extraction and improve efficiency.
• Accessory Integration: Built-in 120V outputs for humidifier and electronic air cleaner support simplified wiring for total home comfort systems.

Common Questions

Does this board support twinning applications?
Yes, the 50A55-843 includes a dedicated "TWIN" terminal for synchronized operation of two furnace blowers, provided both units use the same control board.

How do I handle the '5 flash' rollout error on Trane furnaces?
Standard Trane installations may require the provided RO1 to RO2 jumper wire. If your unit does not use a rollout switch in that specific circuit, the jumper must be installed to complete the loop and prevent a lockout.

What type of ignitor is compatible with this control?
This board is designed specifically for 120V silicon carbide ignitors. It should not be used with 80V silicon nitride ignitors without a proper conversion kit.

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.