Siemens LOA Series

Series Overview

The Siemens LOA Series is a family of burner control units designed primarily for oil-fired burner systems. The LOA platform represents a traditional combustion control architecture based on structured safety timing and flame supervision logic. It is widely used in residential and light commercial oil burner applications.

Although newer digital control platforms are available, LOA units remain in service in many installed burner systems due to their proven reliability and standardized operating sequence.

Position Within Architecture

In an oil burner system, the LOA control unit performs essential functions:

• Managing pre-purge timing
• Controlling ignition sequence
• Supervising flame detection
• Triggering lockout in case of flame failure
• Ensuring automatic shutdown on safety fault

The LOA Series operates based on fixed safety timing logic designed specifically for oil combustion processes.

Typical Applications

LOA Series burner control units are commonly used in:

• Light oil burners
• Residential heating systems
• Commercial oil-fired boilers
• Packaged oil burner assemblies
• Retrofit and replacement applications

Core Functional Characteristics

LOA control units typically provide:

• Structured Sequencing: Precise start-up and shutdown sequences.
• Ignition Control: Integrated management of the ignition transformer.
• Flame Supervision: Continuous monitoring via compatible flame detectors.
• Safety Lockout: Automatic lockout upon flame failure or system fault.
• Fixed Timing: Pre-configured safety timing for standardized operation.
• Plug-in Mounting: Easy installation and replacement with standard bases.

Flame Detection Compatibility

Depending on model configuration, LOA Series units may be used with:

• RAR Series: Infrared flame detectors (oil burners)
• QRB Series: Photoresistive flame detectors (yellow flame)
• Selected compatible sensors: Check specific model data sheets.

Model Differentiation

LOA models may differ based on:

• Ignition timing configuration
• Safety shut-off timing
• Electrical connection layout
• Burner application classification

Selection Guide

When selecting a LOA control unit:

1. Confirm Oil Burner Compatibility: Ensure the unit is rated for your burner type.
2. Verify Ignition Timing: Check the required pre-purge and safety times.
3. Ensure Flame Detector Compatibility: Match with existing sensors (RAR, QRB, etc.).
4. Confirm Electrical Configuration: Verify base connections and voltage.

Positioning Within Siemens Portfolio

Within the Siemens combustion control hierarchy:

• LOA Series → Traditional oil burner control units
• LMO Series → Modern compact burner control units (microcontroller-based)
• LME Series → Enhanced compact control platform
• LDU/LMV Series → Industrial and advanced burner management

The LOA represents the established oil burner control architecture used in many legacy installations.

Integration Within Burner Systems

In a traditional oil burner system, the LOA unit integrates with:

1. Ignition Transformer: Controlled directly by the LOA.
2. Flame Detector: Provides flame signal to the LOA.
3. Oil Solenoid Valve: Managed by the LOA for fuel release.
4. Burner Motor: Sequenced for purge and operation.