Lenox Furnace Manuals

Lenox furnaces are high-efficiency heating systems designed for residential and commercial use, featuring advanced combustion technology, variable-speed blowers, and smart thermostat compatibility. Below are comprehensive sections covering installation, operation, maintenance, troubleshooting, and technical specifications for various Lenox furnace models.

Product Overview

Key components: Heat exchanger, blower assembly, gas valve, ignition system, control board, air filter, thermostat connection.

Component	Description
Heat Exchanger	Stainless steel primary and secondary heat exchangers
Blower Assembly	Variable-speed ECM motor for efficient airflow
Gas Valve	Modulating gas valve for precise temperature control
Ignition System	Hot surface igniter with flame sensor
Control Board	Microprocessor-based control system with LED status
Air Filter	Standard 1-inch or 4-inch media filter slot
Thermostat Connection	Compatible with conventional and smart thermostats
Pressure Switch	Monitors venting system operation
Limit Switch	Prevents overheating by shutting off burner
Flue Pipe Connection	PVC venting for high-efficiency models

Installation Guidelines

Proper installation ensures optimal performance and safety. Follow local codes and manufacturer specifications.

1. Location selection: Install in dry, well-ventilated area with adequate clearance for service access.
2. Venting system: Use approved PVC pipe for intake and exhaust; maintain proper slope and termination clearances.
3. Gas connection: Use black iron pipe with proper thread sealant; test for leaks with soap solution.
4. Electrical wiring: Connect to dedicated 120V circuit; follow NEC requirements for grounding.
5. Ductwork: Ensure proper sizing and sealing; install return air filter grille.
6. Thermostat: Mount on interior wall away from heat sources and direct sunlight.

WARNING! Installation must be performed by qualified HVAC technician. Improper installation can cause carbon monoxide hazards.

Operating Instructions

Power on furnace; follow thermostat settings for proper operation.

1. Startup sequence: Thermostat calls for heat, inducer motor starts, pressure switch closes, igniter heats, gas valve opens.
2. Normal operation: Burner ignites, blower starts after heat exchanger warms, system maintains set temperature.
3. Shutdown sequence: Thermostat satisfied, gas valve closes, blower continues for post-purge cooling.
4. Seasonal operation: Set thermostat to HEAT mode for winter; OFF for summer with AC system.

CAUTION! Do not adjust gas pressure or electrical settings without proper training and equipment.

Technical Specifications

• Models: G60, EL296, SL280, ML180 series
• Input BTU/H: 40,000 to 120,000 BTU
• AFUE Rating: 80% to 98.7% efficiency
• Electrical: 120V AC, 60Hz, 5-15 amp circuit
• Gas Type: Natural gas or propane (conversion kit required)
• Blower Motor: ECM variable speed, 3/4 to 1 HP
• Static Pressure: 0.1 to 0.9 inches water column
• Venting: 2-inch or 3-inch PVC pipe
• Dimensions: Varies by model (typically 21"W x 21"D x 45"H)
• Weight: 120 to 180 pounds

Control Panel Settings

Access control board via front panel cover. LED status light indicates system operation and error codes.

DIP Switch Settings: Blower speeds (HEAT/COOL), timing delays, accessory configurations.

Thermostat Connections: R (24V power), W (Heat), G (Fan), Y (Cool), C (Common). Advanced Models: Support 2-stage heating and variable-speed communication.

Service Mode: Hold specific buttons to enter diagnostic mode for testing components and viewing operational parameters.

Maintenance Procedures

Regular maintenance ensures efficiency and extends system lifespan.

1. Monthly: Check and replace air filter as needed.
2. Seasonal: Inspect vent pipes for obstructions or damage.
3. Annual: Professional inspection of heat exchanger, burners, gas pressure, electrical connections.
4. Biannual: Clean blower assembly and check motor operation.
5. As needed: Lubricate inducer motor bearings if applicable.

Tip: Keep area around furnace clear of combustible materials and maintain proper airflow.

Error Code Diagnostics

LED flash codes indicate specific system faults for troubleshooting.

Flash Code	Description	Resolution
1 Flash	Pressure switch stuck open	Check venting, pressure switch tubing
2 Flashes	Pressure switch stuck closed	Replace pressure switch
3 Flashes	Rollout switch open	Check for restricted airflow, clean heat exchanger
4 Flashes	Open high limit switch	Check airflow, filter, blower operation
5 Flashes	Ignition failure	Check gas supply, igniter, flame sensor
6 Flashes	Gas valve circuit fault	Check wiring, replace gas valve
7 Flashes	Blower fault	Check motor, capacitor, wiring

Safety Features

Multiple safety systems protect against hazardous conditions.

• Flame rollout switches: Detect burner flames outside combustion chamber
• High limit switches: Prevent overheating by shutting off burner
• Pressure switches: Ensure proper venting before gas valve opens
• Flame sensors: Verify burner ignition to prevent gas accumulation
• Carbon monoxide detection: Compatible with CO detectors (not built-in)
• Thermal fuses: Protect against electrical overloads

Warranty Information

Limited warranties vary by model and component.

• Heat Exchanger: 20-year limited warranty
• Parts: 5-year limited warranty
• Labor: 1-year limited warranty
• Registration: Complete online registration within 90 days of installation
• Transferable: Some warranties transfer to new homeowners

Contact Lennox at 1-800-9-LENNOX for warranty claims and service.

Regulatory Compliance

UL certified; meets ANSI Z21.47 standards for gas-fired central furnaces. CSA certified for Canadian installations. Energy Star qualified models available. Complies with Department of Energy efficiency standards. For technical support, visit www.lennox.com or contact 1-800-9-LENNOX.

Troubleshooting Guide

Symptom	Possible Cause	Corrective Action
Furnace won't start	Power, thermostat, door switch	Check circuit breaker, thermostat settings, ensure door closed properly
No heat	Gas supply, igniter, filter	Verify gas valve on, check igniter glow, replace dirty filter
Short cycling	Airflow, limit switch	Clean filter, check blower, inspect limit switch
Blower runs continuously	Thermostat fan setting	Set thermostat from ON to AUTO mode
Unusual noises	Motor, ductwork, bearings	Inspect blower wheel, check duct connections, lubricate if needed
Pilot light issues	Thermocouple, gas valve	Clean pilot assembly, replace thermocouple if faulty

Reset Procedure: Turn thermostat off, wait 30 seconds, turn back on. For lockout conditions, turn power off for 5 minutes then restore.

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