Lennox Furnace Installation Manual G61

The Lennox G61 series furnace is a high-efficiency gas furnace designed for residential heating applications. This model features variable-speed technology, quiet operation, and advanced diagnostic capabilities. The G61 furnace requires professional installation and proper venting to ensure safe and efficient operation. Below are key sections covering safety precautions, installation procedures, electrical connections, startup procedures, maintenance, and troubleshooting.

1. Safety Precautions 2. Installation Requirements 3. Electrical Connections 4. Gas Line Connections 5. Venting System 6. Startup and Commissioning 7. Operating Instructions 8. Maintenance Procedures 9. Troubleshooting Guide 10. Technical Specifications 11. Warranty Information

Safety Precautions

Critical safety information for installers and homeowners.

Hazard	Precaution
Gas Leaks	Check all connections with leak detection solution before startup
Electrical Shock	Disconnect power before servicing or installing
Carbon Monoxide	Ensure proper venting and combustion air supply
Fire Hazard	Maintain proper clearances from combustible materials
Burn Hazard	Allow furnace to cool before handling components

Installation Requirements

Proper installation ensures optimal performance and safety.

Location: Install in clean, dry area with adequate combustion air and service access.
Clearances: Maintain minimum clearances - 1" sides, 1" front, 6" top, 0" back.
Combustion Air: Ensure adequate fresh air supply for proper combustion.
Drain Line: Install condensate drain with proper slope and trap.
Gas Supply: Verify gas type and pressure requirements.

WARNING! Installation must comply with all local codes and regulations. Professional installation required.

Electrical Connections

Proper electrical wiring is essential for safe operation.

Disconnect power before making electrical connections.
Verify voltage: 120V AC, 60Hz single phase.
Connect line voltage wiring to furnace junction box.
Connect thermostat wires to control board terminals.
Install proper fuse or circuit breaker (15A recommended).
Ground furnace according to local electrical codes.

CAUTION! Incorrect wiring can damage furnace components and create safety hazards.

Gas Line Connections

Gas line installation requires certified gas fitter.

Gas Type: Natural gas or LP (conversion kit required for LP)
Inlet Pressure: Natural gas: 7" w.c.; LP gas: 11" w.c.
Manifold Pressure: Natural gas: 3.5" w.c.; LP gas: 10" w.c.
Pipe Size: Minimum 1/2" for runs up to 20 feet
Sediment Trap: Required at gas valve inlet

WARNING! Test all gas connections for leaks before placing furnace in operation.

Venting System

Proper venting is critical for safe operation.

Use only approved PVC pipe for venting (2" minimum diameter).
Maintain proper slope: 1/4" per foot toward furnace.
Maximum vent length: 60 feet equivalent length.
Install condensate drain with proper trap and vent.
Ensure vent termination meets local code requirements.

CAUTION! Improper venting can cause carbon monoxide buildup.

Startup and Commissioning

Follow this procedure for initial startup.

Verify all connections are secure and proper.
Open gas supply valve slowly.
Check for gas leaks at all connections.
Restore electrical power to furnace.
Set thermostat to call for heat.
Verify proper ignition sequence.
Check gas pressure and adjust if necessary.
Measure temperature rise across heat exchanger.
Verify proper vent operation.

Operating Instructions

Understanding furnace operation and controls.

Control Board: LED status lights indicate system operation and fault codes.

Thermostat: Compatible with most standard 24V thermostats.

Blower Speeds: Variable-speed operation for optimal comfort and efficiency.

Ignition Sequence: Hot surface igniter with flame sensor safety.

Safety Controls: Limit switches, pressure switches, and rollout switches.

Maintenance Procedures

Regular maintenance ensures long-term reliability.

Component	Maintenance Interval	Procedure
Air Filter	Monthly	Check and replace if dirty
Burners	Annually	Inspect and clean if necessary
Heat Exchanger	Annually	Visual inspection for cracks
Blower Assembly	Annually	Clean and lubricate if required
Vent System	Annually	Inspect for obstructions

Troubleshooting Guide

Common issues and solutions for the G61 furnace.

Symptom	Possible Cause	Corrective Action
No heat	Thermostat setting, power, gas valve	Check thermostat, verify power, ensure gas valve open
Furnace won't start	Safety switch, limit control	Reset door switch, check limit control
Short cycling	Dirty filter, blocked vent	Replace filter, check vent for obstructions
Blower runs continuously	Thermostat fan setting	Check thermostat fan setting (AUTO/ON)
Error codes displayed	Various system faults	Refer to diagnostic chart in service manual

Technical Specifications

Model Series: G61MP, G61V
Input BTU/h: 40,000 - 120,000
Efficiency: Up to 96.7% AFUE
Electrical: 120V AC, 60Hz, 5.0-8.5 amps
Blower Motor: Variable-speed ECM
Venting: PVC pipe (2" minimum)
Dimensions: Varies by model (approx. 21"W x 21"D x 40"H)
Weight: 120-180 lbs depending on model

Warranty Information

Lennox provides comprehensive warranty coverage for the G61 series.

Heat Exchanger: Limited lifetime warranty

Parts: 10-year limited warranty

Labor: 1-year limited warranty

Registration: Product must be registered within 60 days of installation

For warranty service, contact authorized Lennox dealer. Keep original sales receipt and installation date for warranty claims.

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