Lennox Electric Furnace Service Manual

The Lennox Electric Furnace is a high-efficiency heating system featuring electric heating elements, multi-speed blower motor, integrated control board, safety limit switches, diagnostic LED indicators, and compatibility with various thermostat systems. Designed for residential and light commercial applications with voltage requirements of 120V/240V AC, 60Hz. Below are key sections for safety procedures, technical specifications, installation guidelines, operation instructions, maintenance procedures, and troubleshooting protocols.

1. Features at a Glance 2. Installation Guidelines 3. Initial Setup & Commissioning 4. Technical Specifications 5. Controls and Operation 6. Electrical Connections 7. Maintenance Procedures 8. Safety Features 10. Care & Maintenance Schedule 11. Regulatory Compliance 12. Troubleshooting Guide

Features at a Glance

Key components: Electric heating elements, Blower assembly, Control board, Limit switches, Diagnostic LED, Air filter compartment, Service access panels.

FeatureDescription
Heating elementsMultiple electric heating coils for staged heating
Blower motorMulti-speed ECM motor for efficient airflow
Control boardIntegrated microprocessor for system control
Limit switchesSafety devices to prevent overheating
Diagnostic LEDFlash codes for system status and error reporting
Air filter compartmentStandard 1-inch filter access
Service disconnectExternal power disconnect switch
Thermostat terminalsStandard R, W, G, C, Y connections
High voltage terminal block240V power input connections
Low voltage terminal block24V control circuit connections

Installation Guidelines

Unpack and inspect all components. Verify furnace model matches specifications.

  1. Location selection: Install in dry, well-ventilated area with proper clearances.
  2. Ductwork connection: Secure supply and return air ducts properly.
  3. Electrical connections: Connect high voltage (240V) and low voltage (24V) wiring.
  4. Thermostat wiring: Connect compatible thermostat using standard color coding.
  5. Grounding: Ensure proper equipment grounding per local codes.

WARNING! High voltage present - disconnect power before servicing. Follow all local electrical codes.

Initial Setup & Commissioning

Power on furnace; verify proper operation sequence.

  1. System check: Verify all safety switches are functional.
  2. Blower operation: Test all blower speeds and airflow.
  3. Heating elements: Test each heating stage sequentially.
  4. Thermostat calibration: Verify temperature accuracy and system response.
  5. Airflow measurement: Check static pressure and CFM delivery.

CAUTION! Ensure proper ventilation and combustion air requirements are met.

Technical Specifications

Controls and Operation

Access control board via front service panel. LED diagnostic indicators provide system status.

Control Board: Microprocessor controls heating stages, blower operation, safety monitoring.

Heating Stages: Sequenced activation based on demand. Blower Control: Automatic delay on/off timers. Safety Monitoring: Continuous monitoring of limit switches and sensors. Diagnostic Codes: LED flash patterns indicate specific error conditions. User Interface: Thermostat controls system operation and temperature settings.

Electrical Connections

High voltage: 240V power supply. Low voltage: 24V control circuit. Thermostat: Standard 5-wire connection.

  1. Disconnect all power before making electrical connections.
  2. Verify voltage and phase match furnace specifications.
  3. Use proper wire sizing per NEC requirements.
  4. Ensure all connections are tight and properly insulated.
  5. Test ground continuity before energizing.

Tip: Use torque specifications for terminal connections to prevent loose connections.

Maintenance Procedures

Regular maintenance ensures optimal performance and longevity.

  1. Filter replacement: Change 1-inch filters monthly during heating season.
  2. Blower cleaning: Vacuum blower wheel and housing annually.
  3. Electrical inspection: Check connections and component condition.
  4. Heating elements: Inspect for damage or oxidation.
  5. Limit switches: Test operation and calibration.
  6. Duct inspection: Check for leaks or obstructions.
  7. Safety devices: Verify proper operation of all safety controls.

WARNING! Always disconnect power before performing maintenance. Use proper personal protective equipment.

Safety Features

High Limit Switches: Automatic shutdown if temperatures exceed safe limits. Fusible Links: Thermal fuses for overtemperature protection. Pressure Switches: Airflow monitoring for proper ventilation. Door Safety Switches: Power interruption when service panels are removed.

Care & Maintenance Schedule

Monthly: Filter inspection/replacement. Quarterly: Visual inspection of components. Annually: Comprehensive cleaning and system check.

CAUTION! Only qualified technicians should perform electrical testing and component replacement.

Regulatory Compliance

UL Certified: Meets UL 1995 standards for heating equipment. NEC Compliance: Designed to meet National Electrical Code requirements. Local Codes: Installation must comply with all applicable local building codes. For technical support, contact Lennox Technical Support at 1-800-9-LENNOX or visit www.lennox.com.

Troubleshooting Guide

SymptomPossible CauseCorrective Action
No heatPower supply, thermostat, limit switchCheck circuit breakers, verify thermostat setting, test limit switches.
Blower not runningMotor, capacitor, control boardTest motor windings, check capacitor, verify control board output.
Insufficient heatHeating elements, airflowTest heating element continuity, check for restricted airflow.
Frequent cyclingDirty filter, limit switchReplace air filter, test limit switch calibration.
Error codes displayedVarious system faultsRefer to diagnostic code chart in service manual.

Reset Procedure: Power cycle unit after addressing fault condition.

Technical Support: 1-800-9-LENNOX; www.lennox.com

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