The Lennox Gas Furnace is a high-efficiency heating system designed for residential and light commercial applications. This service manual covers installation, operation, maintenance, and troubleshooting procedures for various Lennox gas furnace models. Below are key sections for safety guidelines, technical specifications, installation procedures, operation instructions, maintenance schedules, and troubleshooting guides.
Critical safety information for proper installation and service of Lennox gas furnace systems.
| Hazard Type | Precaution |
|---|---|
| Gas Leaks | Check all gas connections with leak detection solution before operation |
| Electrical Shock | Disconnect power before servicing electrical components |
| Carbon Monoxide | Ensure proper venting and combustion air supply |
| High Temperature | Allow furnace to cool before servicing heat exchanger |
| Moving Parts | Disconnect power before servicing blower assembly |
| Combustible Materials | Maintain proper clearances from flammable materials |
Detailed technical data for Lennox gas furnace models.
Step-by-step installation guidelines for proper furnace setup.
WARNING! Installation must comply with all local codes and regulations. Only qualified technicians should install gas furnaces.
Understanding the operational sequence of Lennox gas furnace systems.
Overview of furnace control board and diagnostic capabilities.
| Component | Function |
|---|---|
| Integrated Furnace Control (IFC) | Main system controller with diagnostic LED |
| Pressure Switches | Monitor inducer draft and venting |
| Limit Switches | Prevent overheating of heat exchanger |
| Flame Sensor | Detects presence of flame |
| Rollout Switches | Detect flame rollout conditions |
| Gas Valve | Regulates gas flow to burners |
| Ignition System | Hot surface igniter or intermittent spark |
Proper venting installation for safe furnace operation.
CAUTION! Improper venting can cause carbon monoxide poisoning and system failure.
Electrical wiring and connection requirements.
Gas piping and connection specifications.
Recommended maintenance schedule and procedures.
| Maintenance Task | Frequency | Procedure |
|---|---|---|
| Filter Replacement | Monthly | Replace or clean air filter |
| Heat Exchanger Inspection | Annually | Visual inspection for cracks or damage |
| Burner Cleaning | Annually | Clean burners and orifices |
| Blower Cleaning | Annually | Clean blower wheel and housing |
| Vent Inspection | Annually | Check vent pipes for obstructions |
| Gas Pressure Check | Annually | Verify proper manifold pressure |
Common furnace problems and solutions.
| Symptom | Possible Cause | Corrective Action |
|---|---|---|
| Furnace won't start | Power, thermostat, door switch | Check power supply, thermostat settings, door switch engagement |
| No heat | Gas supply, igniter, pressure switch | Verify gas valve open, check igniter, test pressure switch |
| Short cycling | Dirty filter, airflow, limit switch | Replace filter, check airflow, test limit switch |
| Blower won't stop | Thermostat, control board, fan limit | Check thermostat fan setting, test control board, verify fan limit operation |
| Unusual noises | Blower, inducer, heat exchanger | Inspect blower wheel, inducer assembly, heat exchanger for issues |
| Lockout condition | Safety device, flame sense | Check error codes, reset power, clean flame sensor |
Diagnostic LED flash codes for system troubleshooting.
| Flash Pattern | Code | Description |
|---|---|---|
| 1 Flash | Lockout | Ignition failure - check gas, igniter, flame sensor |
| 2 Flashes | Pressure Switch | Pressure switch stuck open or closed |
| 3 Flashes | Limit Circuit | High limit switch open - check airflow, filter |
| 4 Flashes | Flame Rollout | Rollout switch open - check burners, heat exchanger |
| 5 Flashes | Inducer | Inducer motor fault - check motor, capacitor |
| 6 Flashes | Pressure Switch | Pressure switch did not close |
| 7 Flashes | Gas Valve | Gas valve circuit fault |
Service Contact: 1-800-9-LENNOX; www.lennox.com