Goodman Furnace Manual GMH95

The Goodman GMH95 is a high-efficiency gas furnace with 95% AFUE rating, featuring variable-speed blower motor, two-stage gas valve operation, durable heat exchanger construction, electronic ignition system, built-in diagnostic controls, multiple-speed airflow adjustment, safety shutoff features, and compatibility with various thermostat systems. Designed for residential heating applications with natural gas or propane capability. Below are key sections for safety, features, installation, operation, maintenance, and troubleshooting.

Features at a Glance

Key components: Two-stage gas valve, variable-speed blower motor, aluminized steel heat exchanger, electronic ignition system, integrated control board, pressure switches, flame sensor, and diagnostic LED.

Installation Requirements

Professional installation required. Verify local codes and obtain permits.

1. Location: Install in dry, clean area with adequate clearance for service.
2. Venting: Use approved PVC pipe for direct vent installation.
3. Gas Connection: Use black iron pipe with proper sizing for BTU input.
4. Electrical: 120V AC power supply with proper grounding.
5. Condensate Drain: Install neutralizer kit if required by local codes.

WARNING! Gas furnaces produce carbon monoxide; proper venting is critical. Installation must comply with all local codes and manufacturer specifications.

First-Time Setup

Initial startup must be performed by qualified technician.

1. Verify installation: Check all connections, venting, and gas pressure.
2. Electrical connection: Ensure proper voltage and grounding.
3. Gas pressure adjustment: Set manifold pressure per specifications.
4. Blower speed settings: Adjust for proper airflow.
5. Thermostat configuration: Compatible with two-stage operation.

CAUTION! Never operate furnace without proper venting. Test for gas leaks before startup.

Technical Specifications

• Model Series: GMH95
• AFUE Rating: 95%
• Input BTU/H: 40,000 - 120,000 (varies by model)
• Output BTU/H: 38,000 - 114,000 (varies by model)
• Gas Type: Natural gas or propane (conversion kit required)
• Electrical: 120V AC, 60Hz
• Blower Motor: Variable-speed ECM
• Stages: Two-stage gas valve, variable-speed blower
• Venting: PVC pipe (2" or 3" depending on model)
• Warranty: Limited lifetime heat exchanger, 10-year parts

Controls and Settings

Integrated control board manages all furnace operations with diagnostic capabilities.

Control Board Features: LED status light, dip switch settings, terminal connections for thermostat, pressure switch inputs, gas valve control, blower motor control.

Settings: Blower speeds (heating/cooling), temperature rise adjustment, gas pressure settings, diagnostic mode activation. Access control board by removing front panel. Refer to wiring diagram for specific terminal functions.

Venting and Combustion Air

Direct vent system using PVC pipe for both intake and exhaust.

1. Vent pipe sizing: Use manufacturer-specified diameters.
2. Vent termination: Maintain proper clearances from windows and openings.
3. Combustion air: Ensure adequate fresh air supply.
4. Pipe slope: Condensate drain must slope downward.

Tip: Install carbon monoxide detectors in living areas when using gas appliances.

Operating Instructions

Normal operation controlled by thermostat.

1. Thermostat setting: Set to HEAT mode and desired temperature.
2. Startup sequence: Control board initiates pre-purge, ignition, and burner operation.
3. Two-stage operation: First stage for mild weather, second stage for colder conditions.
4. Blower operation: Variable-speed adjusts airflow for optimal comfort.
5. Shutdown: Thermostat satisfied, gas valve closes, blower continues for heat dissipation.

WARNING! If you smell gas, immediately turn off gas supply, evacuate area, and call gas company or fire department.

Maintenance Procedures

Regular maintenance ensures optimal performance and safety.

1. Monthly: Check and replace air filter if dirty.
2. Annual: Professional inspection and cleaning.
3. Burner inspection: Clean and verify proper flame pattern.
4. Heat exchanger: Visual inspection for cracks or damage.
5. Vent system: Check for obstructions and proper drainage.
6. Electrical: Check connections and component operation.

CAUTION! Turn off electrical power and gas supply before performing any maintenance.

Regulatory Information

ANSI Z21.47: Certified for natural gas and propane operation. CSA International: Certified to applicable standards. UL listed components. Installation must comply with National Fuel Gas Code (NFPA 54) and local building codes. For technical support, contact Goodman Manufacturing at 1-877-466-8626 or visit www.goodmanmfg.com.

Troubleshooting Guide

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

Service: 1-877-466-8626; www.goodmanmfg.com