Siemens LME11 / LME21 / LME22 fault 7: Too many losses of flame during operation (limitation of repetitions)
Seven red blinks mean the flame was established and then lost while the burner was running, more often than the burner control allows. LME11… types repeat startup after a loss of flame, up to 3 times per controlled startup, and then lock out. On LME2… types the data sheet lists a loss of flame during operation as a non-alterable lockout without repetition.
Diagnose this with AI
Try Free Boiler Diagnostic Upload a keypad photo, the fault history or a parameter export from your Siemens LME11 / LME21 / LME22. InduQT compares the evidence and suggests the next useful checks.
When it happens
- Burner operation (C–D), after the operating position was reached
- Often after load changes, or when the green lamp has been flashing (flame not ok)
Where it sits in the burner
Supervised functions: Flame supervision, Main fuel delivery.
| Component | Signals to look at | How it fails |
|---|---|---|
| Flame rod | Flame signal | Flame rod or burner ground fault; Scanner no longer sighted on the flame root |
| Flame scanner (UV / IR) | Flame signal | Dirty or fogged scanner sight path; Scanner no longer sighted on the flame root; Detector or amplifier ageing; Electrical noise on signal wiring |
| Main safety shutoff valves | Main fuel valve output, Valve proof of closure | Fuel valve not opening fully; Valve seat leakage or slow closing; Welded, jumpered or miswired contact |
| Fuel supply and regulator | Main gas pressure, Oil pressure | Fuel supply pressure droop; Regulator out of adjustment or sticking |
| Air damper, actuator and linkage | Air damper position, Firing rate | Air/fuel ratio drift; Damper or valve linkage slip; Actuator or feedback fault |
Likely causes and checks
1Faulty or soiled flame detector
- Points to it
- The green lamp flashed (flame not ok) during operation before the lockout; ionization current near the threshold.
- Check
- Measure the ionization current in operation. For an ionization probe the data sheet gives a switching-on threshold of DC 1.5 µA, a detector current of DC 3 µA for reliable operation, and about DC 5 µA as the threshold below which the green lamp flashes (flame not ok) during operation. Clean or reposition the probe, check its ceramic insulator and the burner earthing.
2Faulty or soiled fuel valves
- Points to it
- Flame drops out with valve noise, or gas pressure falls at the burner while the valve is open.
- Check
- Check the gas pressure downstream of the valves in operation and the valve coils and wiring.
3Gas supply pressure dropping
- Points to it
- Flame losses when other gas users start or at the second stage.
- Check
- Trend gas inlet pressure across a full firing cycle; compare with the burner’s minimum.
4Poor adjustment of burner
- Points to it
- Losses follow a service or happen at one stage only; unstable or lifting flame.
- Check
- Have the burner set up across both stages with a combustion analyser; check the air damper and, on LME22, the actuator settings.
Telling it apart
- 7 blinks is flame lost after it was established; 2 blinks is flame never established in the safety time.
- A green lamp that flashes in operation (flame not ok) before the first lockout points to the flame signal rather than the fuel supply.
Evidence to collect
- Blink count after pressing reset for more than 3 seconds
- LME type (LME11 repeats, LME21/LME22 do not)
- Whether the green lamp flashes in operation
- Ionization current in operation at both stages
- Gas pressure trend around the flame loss
Work on fuel trains, burners, pressure vessels and electrical equipment must be done by qualified personnel following the manufacturer’s documentation and local codes. Never bypass a safety device or interlock.