Honeywell PCB (control board) SM07407U

This control board is the burner control in a wall-hung boiler. It manages the ignition sequence and enforces safety times, including pre-purge, ignition, fuel admission, flame proving, and lockout on failure. It reads signals from pressure switches and the flame detector, and drives the ignition transformer, gas valve, and fan. It is intended for Hermann boilers.

Control boards of this type are model-specific and must be matched to the boiler design. Selection is by exact series and type designation, supply voltage, safety and pre-purge times, and flame detection method (ionisation, UV, or IR). The base pattern or plug connection must also match the wiring harness. Confirm the boiler model and the board's factory markings against the original before ordering.