Lennox Gas Furnace Owners Manual

The Lennox Gas Furnace is a high-efficiency heating system designed for residential use, featuring advanced combustion technology, variable-speed blower motors, and smart thermostat compatibility. Below are key sections for safety, features, installation, operation, maintenance, and troubleshooting.

1. Features at a Glance 2. Installation Requirements 3. First-Time Setup 4. Technical Specifications 5. Controls and Settings 6. Operating Instructions 7. Maintenance Schedule 8. Safety Features 9. Care & Cleaning 10. Regulatory Information 11. Troubleshooting

Features at a Glance

Key components: High-efficiency heat exchanger, variable-speed blower, electronic ignition system, smart thermostat interface, air filter compartment, gas valve, pressure switches.

Feature	Description
Heat Exchanger	Stainless steel construction for maximum efficiency and durability
Variable-Speed Blower	Adjusts airflow for optimal comfort and energy savings
Electronic Ignition	Reliable hot surface ignition system
Smart Thermostat Compatible	Works with Lennox iComfort and other smart thermostats
Air Filter System	Easy-access filter compartment for maintenance
Gas Valve	Precise gas flow control for efficient operation
Pressure Switches	Safety devices that monitor combustion air flow
LED Status Light	Diagnostic indicator for troubleshooting
Drain System	Condensate removal for high-efficiency models
Venting System	PVC pipe compatible for sidewall or roof venting

Installation Requirements

Professional installation required. Ensure proper clearances and venting.

Location: Install in well-ventilated area with proper clearances to combustible materials.
Gas Connection: Use approved gas piping and fittings; pressure test required.
Electrical: 120V AC power supply with proper grounding.
Venting: Follow local codes for PVC vent pipe installation.
Drain Line: Install condensate drain line for high-efficiency models.

WARNING! Gas furnaces produce carbon monoxide; proper venting is critical. Only qualified technicians should install.

First-Time Setup

Initial startup must be performed by qualified technician.

System Check: Verify all connections and clearances.
Gas Pressure: Set manifold pressure to specifications.
Combustion Analysis: Check CO levels and efficiency.
Thermostat Setup: Program desired temperature settings.
Test Operation: Run through complete heating cycle.

CAUTION! Do not attempt first-time startup without proper training and equipment.

Technical Specifications

Heating Capacity: 40,000 - 120,000 BTU/h depending on model
Efficiency Rating: Up to 98.7% AFUE
Gas Type: Natural Gas or LP (conversion kit required)
Electrical: 120V AC, 60Hz, 15 Amp circuit
Blower Motor: Variable-speed ECM motor
Sound Level: As low as 68 dBA
Venting: 2" PVC pipe (category IV)
Warranty: Limited lifetime heat exchanger warranty
Dimensions: Varies by model series

Controls and Settings

Access system controls via thermostat or furnace control board.

Thermostat: POWER, MODE (HEAT/COOL/OFF), FAN (AUTO/ON), TEMPERATURE, PROGRAM, HOLD.

Furnace Control Board: POWER switch, LED diagnostic light, pressure switch terminals, gas valve connections, blower motor controls. Settings: Temperature rise, blower speed, gas pressure, fan on/off delays. Advanced: Smart recovery, adaptive intelligent control, humidity control.

Operating Instructions

Use thermostat to control heating operation.

Set Mode: Switch thermostat to HEAT position.
Set Temperature: Adjust to desired comfort level.
Fan Setting: AUTO (runs with heat) or ON (continuous).
Program: Set schedule for energy savings.
Monitor: Listen for normal operation sounds.

Tip: Keep thermostat away from heat sources and direct sunlight for accurate temperature reading.

Maintenance Schedule

Regular maintenance ensures efficiency and longevity.

Monthly: Check air filter; replace if dirty.
Seasonal: Professional inspection before heating season.
Annual: Complete system cleaning and safety check by qualified technician.
Biannual: Ductwork inspection and cleaning if needed.

WARNING! Turn off power and gas supply before performing any maintenance.

Safety Features

Multiple safety systems protect against hazardous conditions.

Safety Feature	Function
Flame Rollout Switch	Shuts off gas if flame extends outside burner area
High Limit Switch	Prevents overheating by shutting off burners
Pressure Switches	Ensure proper venting before ignition
Gas Valve	Automatic shutoff if ignition fails
Carbon Monoxide Detection	Monitors combustion gases (some models)

Care & Cleaning

Regular cleaning maintains efficiency and prevents issues.

Air Filter: Replace every 1-3 months during heating season.
Burners: Professional cleaning annually.
Blower: Vacuum annually when accessible.
Drain System: Flush condensate line seasonally.
Venting: Inspect for obstructions annually.

CAUTION! Never use water or cleaning chemicals on electrical components.

Regulatory Information

UL listed and ANSI certified. Complies with ASHRAE standards. Meets DOE efficiency requirements. Manufactured to ISO 9001 quality standards. For support, visit www.lennox.com or contact 1-800-9-LENNOX. Installation must comply with National Fuel Gas Code NFPA 54 and local building codes.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Furnace won't start	Power, thermostat, gas supply	Check circuit breaker; verify thermostat settings; ensure gas valve is on.
No heat	Pilot/ignition, filter, limit switch	Check for ignition; replace dirty filter; reset high limit switch.
Short cycling	Filter, thermostat, airflow	Clean/replace filter; check thermostat location; ensure vents open.
Blower won't stop	Thermostat fan setting	Set fan to AUTO instead of ON.
Unusual noises	Motor, blower, ductwork	Lubricate motor (if applicable); clean blower; check for loose panels.
LED error code flashing	System fault	Count flashes and refer to diagnostic chart in manual.

Reset: Turn power off for 30 seconds then restore.

Service: 1-800-9-LENNOX; www.lennox.com