Honeywell Electronic control board SM11469U

An electronic control board for wall-mounted gas boilers. It serves as the main controller for ignition sequence and safety functions, handling pre-purge, ignition, fuel admission, flame proving, and lockout on failure. The board manages modulation by adjusting fan speed and gas valve output based on temperature sensor feedback. It is compatible with Baxi Main Four, Eco Four, and Fourtech models, and can replace part numbers JJJ005702450, 005702450, and 5702450. No adjustment is possible on the board itself.

Select a replacement by matching the control board to the specific boiler model; these boards are not interchangeable across different models, even within the same brand. Confirm the exact part number and the boiler model before ordering, as supply voltage and safety times are set by the board's firmware and must match the boiler's design parameters. No adjustment is possible on the board itself.

When a control board fails, the boiler typically enters lockout mode and will not ignite. Common failure modes include loss of flame signal recognition, incorrect safety timing, or communication faults with temperature sensors. The equipment may show a fault code or fail to respond to the thermostat. If the board is mismatched to the boiler model, safety timing errors or valve control issues may occur.