Lennox Furnace Instruction Manual

The Lennox Furnace is a high-efficiency heating system designed for residential use, featuring advanced combustion technology, variable-speed blower motors, and smart thermostat compatibility. This furnace offers multiple efficiency ratings, quiet operation, durable heat exchangers, and integrated safety controls. Below are key sections for safety, features, installation, setup, operation, maintenance, and troubleshooting.

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

Features at a Glance

Key components: High-efficiency heat exchanger, Variable-speed blower motor, Ignition control module, Gas valve, Pressure switches, Filter compartment, Vent connections.

Feature	Description
Heat Exchanger	Durable stainless steel construction for maximum heat transfer
Blower Motor	Variable-speed ECM motor for quiet operation and energy efficiency
Ignition System	Hot surface ignition for reliable startup
Gas Valve	Precise gas flow control for optimal combustion
Pressure Switches	Safety verification of proper venting operation
Filter Access	Easy-access door for filter replacement
Vent Connections	PVC pipe connections for intake and exhaust
Control Board	Microprocessor-based for system monitoring and control
Status Lights	LED indicators for diagnostic information
Thermostat Connection	Compatible with most 24V thermostat systems

Installation

Unpack and inspect all components. Ensure proper clearances and venting requirements.

Position furnace: Place on stable, level surface with proper clearances to combustibles.
Connect gas supply: Use approved gas piping with shutoff valve and sediment trap.
Install venting: Connect PVC pipes for intake and exhaust according to local codes.
Electrical connections: Connect 120V power supply and thermostat wiring.
Ductwork: Connect supply and return ducts securely.

WARNING! Installation must be performed by qualified HVAC technician. Gas connections require leak testing. Ensure proper ventilation.

First-Time Setup

Power on furnace; verify proper operation through startup sequence.

Gas pressure adjustment: Verify and adjust gas pressure to manufacturer specifications.
Blower speed settings: Configure blower speeds for heating mode.
Thermostat configuration: Program thermostat for desired temperature settings.
System check: Verify proper ignition, heating operation, and safety controls.
Airflow verification: Check static pressure and adjust blower if necessary.

CAUTION! Initial startup must be performed by qualified technician. Verify all safety controls are functioning properly.

Specifications

Heating Capacity: 40,000 - 120,000 BTU/h (model dependent)
Efficiency Rating: Up to 98% AFUE
Electrical Requirements: 120V AC, 60Hz
Gas Type: Natural gas or LP (conversion kit required)
Blower Motor: Variable-speed ECM
Heat Exchanger: Stainless steel
Sound Rating: Ultra-quiet operation
Venting: PVC pipe (2" or 3" diameter)
Dimensions: Varies by model
Warranty: Limited lifetime heat exchanger warranty

Controls and Settings

Access control board via front panel. Status lights indicate system operation and fault codes.

Control Board: POWER switch, Status LED, Diagnostic codes, DIP switch settings.

Temperature Control: Thermostat settings (HEAT, OFF, AUTO), Temperature setpoints, Fan control (AUTO, ON). Blower Settings: Heating speed adjustment, Continuous fan operation. Safety Controls: High limit switch, Pressure switches, Flame sensor, Rollout switches. Diagnostic Codes: LED flash patterns for troubleshooting.

Connecting Thermostat

Compatible with most 24V thermostat systems. Standard wiring connections: R, W, G, Y, C.

Turn off power to furnace before wiring.
Connect thermostat wires to control board terminals.
Match wire colors to terminal designations.
Secure connections and restore power.
Test thermostat operation.

Tip: Use programmable thermostat for optimal energy efficiency and comfort.

Operation

Normal heating cycle operation and user controls.

Set thermostat to HEAT mode and desired temperature.
Furnace will initiate startup sequence: inducer motor, pressure switch verification, ignition, gas valve opening.
Once flame is established, blower motor will start after warm-up delay.
When thermostat is satisfied, gas valve closes and blower continues for post-purge.
Fan control: AUTO (cycles with heat) or ON (continuous operation).

WARNING! Do not attempt to adjust gas valve or safety controls. Contact qualified technician for service.

Maintenance

Regular maintenance ensures optimal performance and longevity.

Monthly: Check and replace air filter as needed.
Annual: Professional inspection and cleaning.
Seasonal: Verify proper operation before heating season.
Visual inspection: Check for debris, corrosion, or damage.
Venting: Ensure intake and exhaust pipes are clear.

CAUTION! Turn off power and gas supply before performing any maintenance. Only qualified technicians should service internal components.

Safety Features

Multiple safety systems protect against hazardous conditions.

Flame rollout switches: Detect improper burner operation
High limit switch: Prevents overheating
Pressure switches: Verify proper venting
Flame sensor: Confirms burner ignition
Gas valve: Automatic shutoff in fault conditions
Ignition control: Safe startup sequence

Regulatory Information

UL listed and ANSI certified. Complies with ASHRAE standards. Manufactured to meet or exceed industry safety standards. Natural gas models certified for use with natural gas. LP models require conversion kit. For technical support, visit www.lennox.com or contact 1-800-9-LENNOX.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Furnace won't start	Power, thermostat, switch	Check circuit breaker, thermostat settings, door switch
No heat	Pilot, gas supply, filter	Verify gas valve on, check filter, confirm thermostat call
Short cycling	Filter, limit switch	Replace dirty filter, check for blocked vents
Blower not working	Motor, capacitor, control	Check blower door switch, motor operation
Unusual noises	Motor, blower wheel	Inspect for loose components, debris in blower
Lockout condition	Safety controls	Reset power, check diagnostic lights, call technician

Reset: Turn power off for 30 seconds then restore.

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