Lennox G16 Furnace Manual

The Lennox G16 Furnace is a high-efficiency gas furnace featuring two-stage heating, variable-speed blower motor, durable heat exchanger, electronic ignition, built-in diagnostics, quiet operation, and energy-saving performance. Designed for residential heating applications with AFUE ratings up to 96%, it includes safety features like flame rollout protection, limit switches, and pressure switches. Below are key sections for safety, features, installation, setup, operation, and troubleshooting.

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

Features at a Glance

Key components: Two-stage gas valve, variable-speed blower motor, aluminized steel heat exchanger, electronic ignition system, control board, filter rack, flue outlet, gas valve, pressure switch ports.

Feature	Description
Two-stage heating	Provides efficient low-stage operation for mild weather
Variable-speed blower	Adjusts airflow for optimal comfort and efficiency
Electronic ignition	Hot surface igniter for reliable lighting
Durable heat exchanger	Aluminized steel construction for long service life
Built-in diagnostics	LED status lights for troubleshooting
Quiet operation	Insulated cabinet and variable-speed motor
Filter access	Standard 1-inch filter rack
Gas valve	Two-stage gas control valve
Pressure switch	Ensures proper venting operation
Limit switches	Prevents overheating

Installation

Unpack and inspect contents. Position in approved location.

Gas connection: Use approved black iron pipe with pipe compound; install shutoff valve.
Electrical connection: Connect 120V power supply; install disconnect switch if required.
Vent system: Install PVC vent pipes per local codes; maintain proper slope.
Condensate drain: Connect drain line to suitable drain with trap.
Ductwork: Connect supply and return ducts; ensure proper sizing.

WARNING! Gas appliances can be dangerous; only qualified technicians should install. Ensure proper ventilation and clearances.

First-Time Setup

Power on furnace; follow startup procedure.

Gas pressure check: Verify inlet and manifold pressures per specifications.
Blower speed settings: Adjust cooling and heating speeds per requirements.
Thermostat connection: Connect compatible two-stage thermostat.
System checkout: Run through complete heating cycle; check temperatures.
Customer orientation: Explain operation and maintenance requirements.

CAUTION! Test for gas leaks with soap solution. Verify proper venting before operation.

Specifications

Heating Capacity: 40,000 to 120,000 BTU/hr depending on model
AFUE Rating: Up to 96% efficiency
Stages: Two-stage heating operation
Blower Motor: Variable-speed ECM
Gas Type: Natural gas (LP conversion kit available)
Electrical: 120V, 60Hz, 1.5-8.0 amps depending on model
Vent Material: PVC pipe required
Filter Size: Standard 1-inch or 4-inch media filter
Sound Rating: As low as 65 dBA
Warranty: Limited lifetime heat exchanger warranty

Controls and Settings

Access control board via front panel. Status LED: Green for normal, flashing codes for faults.

Thermostat Connections: R (power), C (common), W/W1/W2 (heat), G (fan), Y/Y1/Y2 (cool)

Heating Stages: First stage (low fire) for mild days, second stage (high fire) for cold days. Blower Speeds: Adjustable for heating and cooling modes. Diagnostic Codes: LED flash patterns indicate specific faults. DIP Switches: Configure blower speeds, timing delays, and other parameters.

Connecting Components

Gas: Black iron pipe with sediment trap. Electrical: 120V power with disconnect. Vent: PVC pipe system. Condensate: PVC drain line with trap.

Turn off gas and electrical power before connecting.
Use proper pipe size for gas line (typically 1/2" to 3/4").
Install union for serviceability in gas line.
Vent pipes must slope upward away from furnace.
Condensate drain requires proper trap and air gap.

Tip: Label all wires and pipes for easy identification during service.

Operating Procedures

Normal heating cycle operation.

Call for heat: Thermostat signals furnace to start.
Inducer motor: Starts first to establish draft.
Pressure switch: Closes when proper draft is established.
Ignition sequence: Hot surface igniter glows, gas valve opens.
Flame detection: Flame sensor confirms ignition.
Blower operation: Starts after heat exchanger warms up.
Cycle completion: Shuts down when thermostat satisfied.

WARNING! Do not attempt to override safety controls. If furnace locks out, call qualified technician.

Safety Features

Flame Rollout Switch: Detects flame outside heat exchanger. Limit Switches: Prevent overheating. Pressure Switches: Ensure proper venting. Ignition Control: Safe lighting sequence. Flame Sensor: Confirms burner operation.

Maintenance & Cleaning

Turn off power and gas before servicing. Replace filter monthly during heating season. Clean flame sensor annually. Inspect heat exchanger for cracks. Clean condensate drain and trap.

CAUTION! Only qualified technicians should service gas components. Keep combustion area clear of debris.

Regulatory Information

ANSI Z21.47: Certified for natural gas operation. UL listed. Complies with U.S. energy efficiency standards. Copyright © Lennox Industries Inc. For support, visit www.lennox.com or contact 1-800-9-LENNOX. Installation must comply with local building codes and utility requirements.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Furnace won't start	Power/thermostat	Check circuit breaker; verify thermostat setting and batteries.
No heat	Gas supply/ignition	Verify gas valve on; check for ignition failure codes.
Short cycling	Filter/limit switch	Replace dirty filter; check for blocked vents or registers.
Blower won't run	Motor/control	Check for loose wires; verify control board output.
Lockout condition	Safety device	Reset power; check LED codes for specific fault.
Unusual noises	Mechanical issues	Inspect blower wheel; check for loose components.

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

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