Lennox Furnace Model SL280V Owner's Manual

The Lennox SL280V is a high-efficiency gas furnace with variable-speed technology, delivering up to 80% AFUE efficiency. This two-stage furnace features quiet operation, durable construction, and advanced diagnostics. 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. 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: Variable-speed blower motor, two-stage gas valve, insulated cabinet, diagnostic LED, flame sensor, hot surface ignitor.

Feature	Description
Variable-speed motor	Provides consistent airflow and quiet operation
Two-stage gas valve	Adjusts heat output for efficiency and comfort
Insulated cabinet	Reduces operating noise
Diagnostic LED	Displays error codes for troubleshooting
Flame sensor	Ensures safe ignition and operation
Hot surface ignitor	Reliable electronic ignition system
Pressure switches	Verify proper venting operation
Limit switches	Prevent overheating
Gas valve	Controls natural gas or propane flow
Blower compartment	Houses circulating air fan

Installation Requirements

Professional installation required. Ensure proper location and clearances.

Location: Install in dry, clean area with adequate combustion air.
Clearances: Maintain 1-inch clearance from combustible materials.
Venting: Use approved PVC vent pipe for direct vent installation.
Gas connection: Use black iron pipe with proper thread sealant.
Electrical: Connect to 120V AC, 60Hz power supply.
Ductwork: Ensure proper sizing and sealing.

WARNING! Gas furnaces produce carbon monoxide. Must be installed by qualified technician. Ensure proper ventilation.

First-Time Setup

Initial startup must be performed by qualified technician.

Verify installation: Check all connections and clearances.
Gas pressure: Adjust manifold pressure per specifications.
Electrical: Connect thermostat and power supply.
Venting: Confirm proper draft and vent pipe installation.
Test operation: Run through complete heating cycle.
Customer orientation: Explain basic operation and maintenance.

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

Specifications

Model: SL280V
Efficiency: Up to 80% AFUE
Stages: Two-stage heating
Motor: Variable-speed ECM
Fuel Type: Natural gas or propane
Input BTU: 40,000 to 120,000 (varies by model)
Voltage: 120V AC, 60Hz
Venting: PVC direct vent
Warranty: Limited lifetime heat exchanger
Sound Level: As low as 65 dB

Controls and Settings

Thermostat controls operation. Furnace includes diagnostic LED and service switches.

Thermostat: HEAT/COOL/OFF, FAN AUTO/ON, temperature setpoint.

Furnace Controls: Power switch, diagnostic LED (flashes error codes), gas valve, pressure switches, limit controls. Blower speeds adjustable for heating and cooling modes. Two-stage operation automatically adjusts based on heating demand.

Operating Instructions

Use thermostat to control furnace operation.

Set thermostat to HEAT mode.
Adjust temperature setpoint above room temperature.
Furnace will ignite and begin heating cycle.
Variable-speed blower adjusts airflow for optimal comfort.
Two-stage operation provides efficient partial-load heating.
For continuous fan operation, set thermostat fan to ON.

Tip: Keep thermostat away from heat sources and drafts for accurate temperature control.

Maintenance Schedule

Regular maintenance ensures efficiency and longevity.

Monthly: Check air filter, replace if dirty.
Seasonal: Professional inspection before heating season.
Annual: Complete professional service including:
- Clean heat exchanger
- Check gas pressure and combustion
- Inspect vent system
- Lubricate motor if required
- Check electrical connections
As needed: Clean flame sensor, check drain system.

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

Safety Features

Multiple safety systems protect against hazardous conditions.

Flame rollout switches
High limit switches
Pressure switches
Flame sensor
Ignition control module
Gas valve safety shutoff

Carbon Monoxide Warning: Install CO detectors near sleeping areas. Have furnace inspected annually.

Care & Cleaning

Regular cleaning maintains efficiency and reliability.

Air filter: Replace every 1-3 months during heating season.
Blower assembly: Vacuum annually when accessible.
Burners: Professional cleaning only.
Drain system: Flush condensate drain annually.
Exterior: Wipe with dry cloth only.

CAUTION! Do not use water or cleaning chemicals on electrical components.

Regulatory Information

UL listed. ANSI Z21.47 compliant. Meets national efficiency standards. Manufactured to ISO 9001 quality standards. For technical support, contact Lennox at 1-800-9-LENNOX or visit www.lennox.com. Serial number located on rating plate inside furnace cabinet.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Furnace won't start	Power, thermostat, switch	Check power supply; verify thermostat settings; ensure service switch is on.
No heat	Gas supply, filter, pilot	Verify gas valve open; check/replace air filter; check for ignition.
Short cycling	Filter, thermostat, limits	Replace dirty filter; check thermostat location; inspect limit switches.
Blower runs continuously	Thermostat setting	Check thermostat fan setting (AUTO/ON).
Unusual noises	Motor, ductwork, components	Inspect blower wheel; check duct connections; have professional inspect.
Error code flashing	System fault	Count LED flashes and refer to diagnostic chart in service manual.

Reset: Turn power off for 30 seconds, then restore.

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