Honeywell PCB (control board) SM11456AU

Honeywell SM11456AU is an electronic control board (PCB) for gas boilers and heating systems, used as an OEM component in various European brands such as Baxi and Westen. It manages ignition sequence, enforces safety times, and monitors pressure switches, flame signal, and temperature sensors. The board drives the gas valve, ignition transformer, fan, and circulation pump. It is identified by manufacturer code 10206952 and model SM11456A, with the suffix 'U' indicating a specific revision or climate version.

Parts of this type are selected by the boiler model's electrical supply, required safety and pre-purge times, and the type of flame detection (ionisation, UV, or IR). Before ordering, visually compare the board's appearance, including connector layout, jumpers, fuses, and mounting hole locations, with the old board. Check the part number on the old board; if it matches SM11456AU or SM11456A, compatibility is guaranteed. If the old board has a different number, consult a manager, as boards may differ across series.

When control boards of this kind fail, the boiler may not ignite, shut down unexpectedly, or display error codes related to flame loss or sensor faults. Symptoms can include the fan running but no ignition, or the pump operating without heat. Check for visible damage like burnt components, loose connections, or blown fuses, and verify sensor readings and flame signal.