Siemens controller

The Siemens LMO14 is a microprocessor-based burner controller designed for the automatic start-up, operating supervision and safe shutdown of forced-draught liquid-fuel burners. It is primarily used with compact single-stage oil burners in domestic and light commercial heating equipment.

The controller manages the burner operating sequence, including the oil preheater, burner motor, ignition equipment and fuel valve. It continuously monitors the flame signal and initiates a safety lockout if a flame is not established within the permitted safety time or if an unsafe operating condition is detected.

Yellow-burning flames can be supervised using compatible Siemens QRB1, QRB3 or QRB4 flame detectors. Blue-burning flames can be monitored using a compatible Siemens QRC1 blue-flame detector. The exact detector must be selected according to the burner design and complete LMO14 model reference.

A multicolour LED provides operating-status and fault information. The controller supports manual reset and electrical remote reset, undervoltage detection, oil-preheater monitoring, restart limitation and digitally controlled operating sequences.

For safety, the LMO controller automatically performs a controlled interruption and restart after 24 hours of continuous burner operation. This ensures that safety-related start-up checks are repeated during extended heating demand.

The LMO series has housing dimensions, electrical connection technology and flame-detector compatibility corresponding to the Siemens LOA oil-burner control family. However, replacement must be approved for the specific burner because operating sequences, safety times, prepurge times and wiring requirements may differ.

Typical applications include domestic oil burners, heating boilers, hot-water boilers, kerosene burners, light commercial heating systems and automatic forced-draught liquid-fuel burners.

Installation, wiring, flame-detector selection, commissioning and lockout diagnosis must be performed by qualified burner-service personnel. The controller must not be opened, modified or repaired, and the burner must be isolated from the electrical supply before any wiring work.