Lennox Furnace Installation Manual G61MP

The Lennox G61MP is a high-efficiency gas furnace featuring variable-speed technology, two-stage heating operation, SilentComfort™ technology, Duralok™ heat exchanger, and compatibility with various thermostat systems. This manual covers safety procedures, installation requirements, electrical connections, gas line connections, ventilation setup, startup procedures, and maintenance guidelines for proper installation and operation.

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

Safety Precautions

Critical safety information for proper furnace installation and operation.

Hazard	Precaution
Gas Leaks	Check all connections with soap solution; never use open flame
Electrical Shock	Disconnect power before servicing; follow local electrical codes
Carbon Monoxide	Ensure proper ventilation; install CO detectors in living areas
Fire Hazard	Maintain clearance from combustibles; keep area clean
Burn Risk	Allow furnace to cool before servicing; wear protective gear

Installation Requirements

Proper installation site preparation and requirements.

Location: Install in clean, dry area with adequate clearance (minimum 24" front, 6" sides, 1" rear).
Combustion Air: Ensure sufficient combustion and ventilation air supply.
Leveling: Place on solid, level surface to prevent stress on heat exchanger.
Ductwork: Connect to properly sized and sealed duct system.
Clearances: Maintain required clearances from combustible materials.

WARNING! Installation must comply with local building codes and manufacturer specifications. Professional installation recommended.

Electrical Connections

Wiring requirements and electrical connections.

Power Supply: Connect to dedicated 120V, 15A circuit with proper grounding.
Thermostat Wiring: Use 18-gauge thermostat cable; follow wiring diagram.
Grounding: Ensure proper equipment grounding per NEC requirements.
Low Voltage: Connect control circuit per provided schematic.
Safety Switches: Verify door safety switch operation.

CAUTION! All electrical work must be performed by qualified personnel following local codes.

Gas Line Connections

Natural gas or propane connection procedures.

Gas Type: Verify furnace is configured for correct gas type (natural or LP).
Pipe Sizing: Use proper pipe size based on length and BTU requirements.
Connection: Use pipe joint compound rated for gas applications.
Pressure Test: Test gas line at 14" W.C. for 10 minutes with no pressure drop.
Gas Valve: Connect to factory-provided gas valve with proper fittings.

WARNING! Gas connections must be made by licensed professional. Always leak test with soap solution.

Ventilation System

Vent and combustion air piping requirements.

Vent Material: Use PVC, CPVC, or ABS pipe as specified.
Vent Sizing: Follow manufacturer tables for proper pipe diameter.
Slope: Maintain 1/4" per foot slope back to furnace.
Terminations: Install vent and air intake terminations per code requirements.
Clearances: Maintain required clearances from windows, doors, and air intakes.

Startup Procedures

Initial startup and system verification.

Pre-start Checklist: Verify all connections, clearances, and settings.
Gas Pressure: Adjust manifold pressure to specified setting (3.5" W.C. natural gas).
Ignition Sequence: Observe proper ignition and flame verification.
Temperature Rise: Measure temperature rise; adjust blower speed if necessary.
Safety Controls: Test limit switches and safety controls for proper operation.

CAUTION! Never bypass safety controls. Verify proper operation before leaving installation.

Operating Instructions

Normal furnace operation and control settings.

Thermostat: Compatible with most 24V thermostats; recommended for optimal performance with Lennox iComfort thermostat.

Operation Modes: Two-stage heating with variable-speed blower. Stage 1 for moderate conditions, Stage 2 for extreme cold. Blower adjusts automatically for optimal comfort and efficiency.

LED Codes: Control board displays status codes via LED flashes for troubleshooting.

Maintenance Guidelines

Routine maintenance requirements for optimal performance.

Monthly: Check air filter; replace when dirty.
Annual: Professional inspection and cleaning recommended.
Blower: Clean blower assembly and motor annually.
Heat Exchanger: Visual inspection for cracks or damage.
Vent System: Inspect for obstructions or damage.

Tip: Keep area around furnace clean and free of combustible materials.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Furnace won't start	Power, thermostat, door switch	Check circuit breaker; verify thermostat setting; ensure door closed properly.
No heat	Gas supply, ignition	Verify gas valve on; check for ignition failure; inspect flame sensor.
Short cycling	Filter, limit switch	Replace dirty filter; check for blocked vents; verify proper airflow.
Blower not working	Motor, capacitor, control	Check blower motor; test capacitor; verify control board operation.
Error codes	Various faults	Refer to LED flash codes in troubleshooting guide.

Specifications

Model: G61MPV
Input BTU/H: 40,000 - 120,000 (varies by model)
AFUE Rating: Up to 96.7%
Stages: Two-stage heating
Blower: Variable-speed ECM motor
Voltage: 120V, 60Hz
Gas Type: Natural or LP (field convertible)
Vent Material: PVC/CPVC approved
Sound Level: As low as 68 dBA

Warranty Information

Limited warranty coverage: 20-year limited warranty on heat exchanger, 5-year limited warranty on functional parts. Warranty registration required within 60 days of installation. Professional installation required for warranty validation. For warranty service, contact authorized Lennox dealer.

Service: Contact authorized Lennox dealer for service. For dealer locator or technical support, visit www.lennox.com or call 1-800-9-LENNOX.