Honeywell Electronic board SM11454U

The Honeywell SM11454U is an electronic control board (PCB) designed for use in modern wall-hung boilers. It manages the ignition and safety sequence for the burner, reading signals from flame, pressure, and temperature sensors to control the ignition transformer, gas valve, fan, and circulation pump. This board enforces programmed safety times, including pre-purge, ignition trial, flame proving, and lockout on failure. It is compatible with Baxi ECO-3 1.240 Fi, 240 Fi, 240 i, 280 Fi, and ENERGY TOP 24 boilers, and is an OEM equivalent to part number 5686920.

Parts of this type are selected by matching the exact original board designation and boiler model, as they are not interchangeable across different models or series. Before ordering, verify the boiler model and the original part number. The board's supply voltage, safety times, and flame detection method are fixed by design and must correspond to the boiler's logic.

When control boards of this kind fail, common symptoms include the boiler not igniting, intermittent operation, or lockout without an obvious cause. Failure may result from electrical surges, moisture, or component aging. Check for visible damage, loose connections, and ensure the board receives correct power and signals from sensors.