Burner Sequence Controller LOA 24 for Gas, Oil, or Dual Fuel Burners (230V AC)

Product Details

The Siemens LMO series consists of microprocessor-based oil burner controllers used for the startup and supervision of forced draft oil burners. They are the modern, electronic replacement for the older, purely mechanical LOA series. 1. Popular LMO Models The model number typically indicates the burner stage (single or two-stage) and the specific timing/functionality. Model Burner Stages Application Safety Time (TSA) LMO14 Single-stage Standard small burners ($< 30$ kg/h) $10$ seconds LMO24 Two-stage Medium-sized boilers $10$ seconds LMO44 Single-stage Small stationary air heaters $5$ seconds LMO64 Single-stage For high-pressure/specialized oil burners $5$ seconds 2. Technical Specifications Mains Voltage: $230\text{V AC}$ or $120\text{V AC}$ (Suffix A2 = $230\text{V}$, A1 = $120\text{V}$). Frequency: $50\dots 60\text{ Hz}$. Power Consumption: Approx. $12\text{ VA}$. Flame Monitoring: Optical: QRB series (Yellow flame). Blue Flame: QRC series. Protection Class: IP40. Operating Temp: $-20\text{°C}$ to $+60\text{°C}$. Service Life: $250,000$ start cycles (approx. 10 years). 3. Key Functional Features Multicolor LED Indicator: The transparent reset button provides visual status: Green: Operation (flame OK). Yellow: Pre-purge/Ignition phase. Red: Fault/Lockout. Flashing Red: Error code diagnostic mode. Undervoltage Detection: If the voltage drops below $165\text{V}$ (for $230\text{V}$ models), the controller prevents startup or shuts down safely. Oil Pre-heater Support: Includes dedicated terminals to wait for the oil heater to reach the correct temperature before starting the motor. Bridging Contact: Integrated contact for oil pre-heaters to ensure they remain hot during operation. 4. Fault Diagnostics (Blink Codes) If the controller locks out (Red light), holding the reset button for $>3$ seconds will trigger a blink sequence: Blink Code Fault Description 2x No flame at the end of safety time ($TSA$). 4x Extraneous light (flame signal detected during pre-purge). 7x Loss of flame during operation (too many repetitions). 8x Time-out for oil pre-heater (heater took too long to reach temp). 10x Wiring error or internal controller failure. 5. Compatibility & Retrofitting The LMO series was designed with the same footprint as the old LOA series. Direct Swap: You can usually replace an LOA24 with an LMO24 using the existing terminal base (AGK11). Upgrade Benefit: Switching from LOA to LMO adds undervoltage protection and more precise electronic timing.