Siemens Burner Sequence Controller LME 21 / LME 22 (230 V AC)

Product Details

The Siemens LME21 and LME22 are both microprocessor-based burner controllers used for the startup and supervision of 1- or 2-stage gas or gas/oil burners. While they look identical and share the same base, they differ significantly in how they handle actuator control for high/low fire. 1. The Core Difference LME21: Designed for 2-stage burners without integrated actuator control. It switches between stages but does not manage the timing of an air damper motor. LME22: Designed for 2-stage burners with integrated actuator control. It includes specific "running times" in its sequence to allow an air damper (actuator) to move between the "low fire" and "high fire" positions. 2. Common Technical Specifications These specifications apply to both the LME21 and LME22 series: Feature Details Mains Voltage 230V AC (+10% / -15%) or 120V AC (C1 models) Frequency 50–60 Hz (±6%) Power Consumption Approx. 12 VA Flame Supervision Ionization probe or UV detector (QRA... with AGQ3 ancillary) Degree of Protection IP40 (provided by the installer) Operating Temp -20°C to +60°C Weight Approx. 160g Design Lifetime 250,000 startup cycles (approx. 10 years) 3. Sequence & Timing Models  The model number determines the specific pre-purge and safety time. LME21 Common Models Model Pre-purge (t1​) Safety Time (TSA) LME21.130C2 7 seconds 3 seconds LME21.330C2 30 seconds 3 seconds LME21.350C2 30 seconds 5 seconds LME22 Common Models (Includes Actuator Running Time) Model Pre-purge (t1​) Safety Time (TSA) Actuator Time LME22.232C2 20 seconds 3 seconds 20 seconds LME22.233C2 20 seconds 3 seconds 30 seconds LME22.331C2 30 seconds 3 seconds 12 seconds 4. Terminal Functions (Wiring Logic) Both use the same 13-pin plug-in base (AGK11), but their outputs vary: Terminal 1: Phase (L) Terminal 2: Neutral (N) Terminal 3: Burner Motor / Air Pressure Switch (Input/Output) Terminal 4: Ignition Transformer Terminal 5: Fuel Valve 1 (Stage 1) Terminal 6: LME21: Fuel Valve 2 (Stage 2) | LME22: Actuator control signal Terminal 10: Reset button / Fault signal output Terminal 12: Safety Loop / Thermostat 5. Diagnostics (Multicolor LED) The reset button serves as a visual indicator: Flashing Yellow: Pre-purge or waiting for air pressure signal. Flashing Green: Safety time / Flame established. Solid Green: Burner in operation (normal). Solid Red: Lockout / Fault. (Refer to the "Pulse Codes" in the previous message to diagnose the number of red flashes). Important Note: When replacing an older LGB or LMG series controller with an LME, you must ensure the base wiring matches.