Siemens Burner control box LFL1.122

The Siemens LFL1.122 is an electromechanical burner control box for intermittent operation of forced-draft gas, oil or combined burners. It manages start-up and flame monitoring for multi-stage or modulating burners; operating voltage is 230 V, pre-purge time 10 s, pre-ignition time 4 s, safety time 2 s, post-purge time 10 s, and total start-up sequence duration 30 s. The control requires verification of the air pressure switch and uses spark ignition. If the flame is not established, it locks out for manual reset.

Replacement control boxes of this type are selected by matching the exact series and type designation, supply voltage, required safety time and pre-purge time, and flame-detection method. The mechanical mounting may be a base or a plug-in pattern, and both the mounting pattern and the wiring-base connections must match the existing installation. Before ordering, compare the nameplate voltage and timing values with the old unit and verify the base configuration, because controls from different series are not interchangeable and a mismatched safety time is hazardous.

If the flame is not proved within the safety time during start-up, this kind of control enters a fault lock-out and the burner stays off until the manual reset is pressed. The control also monitors the air and system pressure switches and prevents the start-up sequence from continuing when these switches are not confirmed. To diagnose repeated lock-outs, note at which step in the sequence the control stops and verify that all monitored signals appear in the correct order.