Lennox Elite 90 Gas Furnace Manual

The Lennox Elite 90 is a high-efficiency gas furnace with AFUE ratings up to 90%, featuring variable-speed blower technology, electronic ignition, multi-speed operation, built-in diagnostics, and quiet operation. Designed for residential heating applications with natural gas or propane capability. Below are key sections for safety, features, installation, operation, maintenance, and troubleshooting.

Features at a Glance

Key components: Variable-speed ECM blower motor, hot surface ignitor, sealed combustion chamber, aluminized steel heat exchanger, integrated control board, pressure switches, flame sensor, and rollout switches.

Installation Requirements

Professional installation required. Verify local codes and obtain permits.

1. Location: Install in dry, clean area with adequate clearance for service.
2. Venting: Use approved PVC pipe for combustion air and flue gas.
3. Gas Supply: Connect to properly sized gas line with shutoff valve.
4. Electrical: Connect to 120V AC power with proper grounding.
5. Ductwork: Ensure properly sized and sealed duct system.

WARNING! Gas furnaces produce carbon monoxide. Proper venting is critical. Installation by qualified technician required.

First-Time Setup

Initial startup must be performed by qualified technician.

1. Verify installation: Check all connections, clearances, and venting.
2. Gas pressure: Set manifold pressure per specifications.
3. Electrical: Verify proper voltage and grounding.
4. Startup sequence: Follow manufacturer's startup procedure.
5. System check: Verify proper operation of all safety controls.
6. Customer orientation: Explain thermostat operation and basic maintenance.

CAUTION! Never bypass safety controls. Carbon monoxide poisoning hazard.

Technical Specifications

• AFUE Rating: Up to 90%
• Input BTU/h: 40,000 to 120,000 (model dependent)
• Output BTU/h: 36,000 to 108,000 (model dependent)
• Gas Type: Natural gas or LP (with conversion)
• Manifold Pressure: Natural gas: 3.5" WC, LP: 10" WC
• Electrical: 120V AC, 60Hz, 15 amp circuit
• Blower Speeds: Multi-speed with variable capability
• Venting: 2" PVC pipe minimum
• Sound Level: As low as 65 dB
• Dimensions: Varies by model (typically 21"W x 21"D x 40"H)

Controls and Settings

Integrated control board with LED status lights and diagnostic codes.

Thermostat: Compatible with most 24V thermostats. Recommended: Programmable thermostat for optimal efficiency.

Control Board: Monitors system operation, provides diagnostic codes via LED flashes. Settings: Blower speed adjustments, timing delays, diagnostic mode. Safety Controls: High limit switch, flame rollout switch, pressure switches, flame sensor.

Venting and Combustion Air

Direct vent system using PVC pipe for both intake and exhaust.

1. Vent pipe: Use schedule 40 PVC, CPVC, or approved ABS.
2. Vent termination: Maintain proper clearances from windows, doors, and vents.
3. Combustion air: Provide adequate fresh air for proper combustion.
4. Vent length: Follow manufacturer's guidelines for maximum vent run.

Tip: Install carbon monoxide detectors near sleeping areas.

Operating Instructions

Operate via compatible thermostat.

1. Set thermostat to desired temperature.
2. System will automatically cycle on and off to maintain temperature.
3. For continuous fan operation, set thermostat to "FAN ON" position.
4. Seasonal shutdown: Turn off gas and electrical power if not used for extended periods.
5. Emergency shutoff: Locate and familiarize with gas shutoff valve location.

WARNING! Never operate without proper venting. Carbon monoxide hazard.

Maintenance Procedures

Annual professional maintenance recommended. Basic homeowner maintenance:

1. Air filter: Replace every 1-3 months during heating season.
2. Visual inspection: Check for obstructions, corrosion, or damage.
3. Vent pipes: Ensure clear of debris, snow, or ice.
4. Burner compartment: Professional cleaning required annually.
5. Blower assembly: Professional cleaning and lubrication.

CAUTION! Turn off gas and electrical power before any maintenance.

Safety Features

Multiple safety systems protect against hazardous conditions.

Regulatory Information

UL listed and ANSI certified. Complies with U.S. Department of Energy efficiency standards. Manufactured to meet or exceed ASHRAE standards. Copyright © Lennox Industries Inc. All rights reserved. For technical support, contact Lennox at 1-800-9-LENNOX or visit www.lennox.com.

Troubleshooting

Diagnostic Codes: Refer to control board LED flash patterns for specific error codes.

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