Goodman GMS80904BN Gas Furnace Manual

The Goodman GMS80904BN is a high-efficiency gas furnace with 80% AFUE rating, single-stage operation, multi-speed blower, and compatibility with standard thermostat systems. Designed for residential use with natural gas, it features electronic ignition, aluminized steel heat exchanger, and safety controls including flame rollout and limit switches. Below are key sections for safety, installation, operation, maintenance, and troubleshooting.

1. Safety Information 2. Installation Requirements 3. Technical Specifications 4. Control System Overview 5. Venting and Combustion Air 6. Electrical Connections 7. Startup and Operation 8. Maintenance Procedures 9. Troubleshooting Guide 10. Warranty Information

Safety Information

Critical safety precautions for installation and operation.

Hazard	Precaution
Gas Leaks	Install gas leak detector; check all connections with soap solution
Carbon Monoxide	Install CO detectors; ensure proper venting
Electrical Shock	Disconnect power before servicing
Fire Hazard	Keep combustible materials away from furnace
Burn Risk	Allow furnace to cool before servicing

WARNING! Installation must be performed by qualified HVAC technician only.

Installation Requirements

Proper installation guidelines and requirements.

Location: Install in clean, dry area with adequate clearance (minimum 24" front, 6" sides)
Gas Supply: 3/4" black iron pipe with sediment trap; test for leaks
Electrical: 120V AC, 15 amp dedicated circuit with proper grounding
Venting: Category I venting; follow local codes for vent pipe sizing
Combustion Air: Ensure adequate fresh air supply per installation requirements

CAUTION! Improper installation may create hazardous conditions.

Technical Specifications

Model: GMS80904BN
Input BTU: 90,000 BTU/h
Output BTU: 72,000 BTU/h
AFUE: 80%
Gas Type: Natural Gas
Gas Pressure: 3.5" WC natural gas
Blower Motor: Multi-speed PSC
Electrical: 115V/60Hz/1Ph
Dimensions: 21" W x 21" D x 40" H
Venting: Category I, 4" diameter

Control System Overview

Integrated furnace control board with LED status indicator.

Component	Function
Control Board	Main system controller with diagnostic codes
Gas Valve	Regulates gas flow to burners
Igniter	Hot surface igniter for burner ignition
Flame Sensor	Detects burner flame presence
Pressure Switch	Verifies inducer operation
Limit Switch	Prevents overheating
Rollout Switch	Detects flame rollout condition

Venting and Combustion Air

Proper venting system requirements for safe operation.

Vent Pipe: Use approved Category I vent material; maintain proper slope
Termination: Roof or sidewall vent per local codes; maintain clearances
Combustion Air: Provide adequate air supply; follow manufacturer guidelines
Vent Length: Maximum equivalent vent length: 40 feet with two 90° elbows

WARNING! Inadequate venting can cause carbon monoxide poisoning.

Electrical Connections

Wiring and electrical connection requirements.

Power Supply: 115V AC, 60 Hz, properly grounded circuit
Thermostat: Standard 24V connections (R, W, G, C, Y)
Blower Speeds: Adjustable cooling and heating speeds
Safety Switches: Properly wire door safety switch

CAUTION! All electrical work must comply with NEC and local codes.

Startup and Operation

Proper startup sequence and normal operation.

Power On: Restore electrical power to furnace
Thermostat Call: Set thermostat above room temperature
Ignition Sequence: Inducer motor starts, pressure switch closes, igniter heats, gas valve opens
Flame Detection: Flame sensor confirms ignition, main burners operate
Blower Operation: Blower starts after warm-up delay
Cycle Completion: Furnace shuts down when thermostat satisfied

Maintenance Procedures

Regular maintenance schedule and procedures.

Maintenance Item	Frequency	Procedure
Air Filter	Monthly	Replace or clean filter
Burner Inspection	Annually	Clean burners and inspect flame pattern
Heat Exchanger	Annually	Visual inspection for cracks or damage
Blower Assembly	Annually	Clean blower wheel and housing
Vent System	Annually	Inspect for obstructions or damage

Troubleshooting Guide

Symptom	Possible Cause	Corrective Action
No heat	Thermostat setting, power, gas supply	Check thermostat, circuit breaker, gas valve
Furnace won't start	Door switch, limit switch, pressure switch	Ensure door closed, check switch continuity
Short cycling	Dirty filter, blocked vent, overheating	Replace filter, check venting, verify airflow
Blower runs continuously	Thermostat fan setting, control board	Check thermostat fan setting, control board
Lockout condition	Ignition failure, flame sense	Reset power, check igniter and flame sensor

LED Error Codes: Refer to control board LED flash patterns for specific diagnostics.

Warranty Information

Goodman limited warranty coverage.

Heat Exchanger: Limited lifetime warranty
Parts: 10-year limited warranty
Labor: Refer to specific labor warranty terms
Registration: Product must be registered within 60 days of installation

For warranty service, contact authorized Goodman dealer. Keep original sales receipt and installation date.

Technical Support: 1-877-GOODMAN | www.goodmanmfg.com