Troubleshooting
35
Cause of fault Corrective action
Internal fault burner control unit or interference Check electrode settings.
Check wiring harness plug X13 for proper connection or
damage.
Check whether flue gas system is leak-tight.
If after corrective action fault “FE” still appears on display
replace LGM 29.
Safety chain was activated (fixed high limit) Check fixed high limit (see page 43). Bleed air from t he
heating system.
Fan speed too high at start (maximum fan rpm exceeded). Fan or fan electronics defective.
Replace RLS 154 electric f an control.
Replace LGM 29 and/or burner assembly.
Fan speed too low at start (incorrect fan rpm). Check fan and flue gas system.
Air pressure threshold for ignition level is not reached.
Feedback voltage signal to LGM 29 not available.
Check fan plug, fan, differential pressure sensor (see page 41)
and inlet air damper (flapper).
Check flue gas system for proper sizing and functioning.
Fan speed incorrect. Check fan and flue gas system.
Fan speed too high prior to ignition (incorrect fan rpm). Check fan and flue gas system.
Fault fan speed Check fan and flue gas system.
No flame signal Check electrical connections (see page 11).
Purge air from gas line (for LP gas, purge air several times).
Measure ionization current (see page 24).
Check gas pressure (see page 13).
Check gas combination valve (see page 13).
Check ignition transformer.
Check ignition electrodes (see page 20).
Check condensate drain (see page 20).
Check power supply polarity (L,N,G).
Check proper grounding.
Check #158 plug on (replacement) LGM 29 is installed
Basic level of air pressure threshold in standby mode not
correct.
Check differential air pressure sensor (see page 41).
Check wiring harness and connection to air pressure sensor.
Severe wind conditions in vent system. Protect outside wall vent termination from severe winds.
Flame signal still present after switching off. Check gas combination valve (see page 13).
Check electrode block (see page 20).
Reset button “EU“ pressed repeatedly or while burner is
running.
Power ON/OFF boiler / acknowledge fault.
Press reset button ”EU” once.
5285 961 v1.3
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