Goodman Furnace GMH950703BX Installation Manual

The Goodman GMH950703BX is a high-efficiency gas furnace with 95% AFUE rating, multi-speed blower, electronic ignition, and compatibility with single-stage thermostats. Designed for residential installation, it features durable heat exchanger construction, diagnostic LED light, and safety controls. Below are key sections for safety, specifications, installation procedures, wiring, startup, and troubleshooting.

Features at a Glance

Key components: Two-stage gas valve, induced draft blower, hot surface ignitor, multi-speed PSC blower motor, diagnostic LED, pressure switches, and limit controls.

Safety Precautions

Read all instructions before installation. Follow local codes and manufacturer guidelines.

1. Disconnect power before servicing: Turn off electrical power at disconnect switch.
2. Gas line safety: Check for leaks with soap solution; never use open flame.
3. Venting clearance: Maintain proper clearance from combustible materials.
4. Carbon monoxide: Install CO detectors in living areas near bedrooms.

WARNING! Failure to follow safety procedures can result in fire, explosion, property damage, personal injury, or death. Installation must be performed by qualified HVAC technician.

Installation Requirements

Verify local codes and obtain necessary permits before installation.

1. Location: Indoor installation only; protected from weather and flooding.
2. Clearance: Minimum 24 inches front service clearance; 1 inch sides and rear.
3. Combustion air: Ensure adequate combustion and ventilation air supply.
4. Ductwork: Properly sized and sealed duct system required.
5. Electrical: Dedicated 115V circuit with proper grounding.

CAUTION! Do not install in areas where flammable liquids or vapors are present.

Specifications

• Model: GMH950703BX
• Input BTU/H: 70,000
• Output BTU/H: 66,500
• AFUE: 95%
• Gas Pressure: Natural Gas 3.5" WC, LP Gas 10" WC
• Electrical: 115V/60Hz, 1.5A
• Blower Speeds: Cooling 1075 CFM, Heating 800 CFM
• Vent Size: 2" or 3" PVC/CPVC
• Dimensions: 21"W x 45"H x 26"D
• Shipping Weight: 125 lbs

Installation Procedures

Follow step-by-step installation sequence for proper operation.

1. Position furnace: Place on level surface, ensure proper clearances.
2. Install filter rack: Mount 16x25x1 filter rack on return air side.
3. Connect ductwork: Seal all joints with approved duct sealant.
4. Install vent pipes: Follow PVC venting guidelines for proper slope.
5. Connect gas line: Use black iron pipe with proper thread sealant.
6. Electrical connections: Wire thermostat, power, and ground connections.
7. Install condensate drain: Route to floor drain with proper trap.

Tip: Use bubble level to ensure furnace is perfectly level for proper condensate drainage.

Electrical Wiring

All electrical work must comply with NEC and local codes.

1. Disconnect power: Turn off power at main electrical panel.
2. Line voltage: Connect 115V power to furnace junction box.
3. Thermostat wiring: Connect R, W, G, C terminals for basic operation.
4. Ground connection: Connect equipment grounding conductor.
5. Blower door switch: Ensure proper connection for safety interlock.

WARNING! Incorrect wiring can cause equipment damage, fire hazard, or void warranty.

Gas Line Connection

Gas piping must be sized according to local codes and appliance requirements.

1. Pipe sizing: Minimum 1/2" black iron pipe for natural gas.
2. Shutoff valve: Install manual gas shutoff valve within 6 feet.
3. Drip leg: Install sediment trap before gas connection.
4. Leak testing: Test all connections with soap solution at 14" WC.
5. Gas valve adjustment: Set manifold pressure to 3.5" WC for natural gas.

CAUTION! Never use Teflon tape on flare fittings; use approved pipe dope only.

Venting Requirements

PVC venting system must be properly designed and installed.

1. Vent material: Schedule 40 PVC or CPVC pipe.
2. Vent sizing: 2" minimum diameter for up to 50 feet total length.
3. Slope: 1/4" per foot back toward furnace for condensate drainage.
4. Termination: Minimum 12" above ground level, 3 feet from openings.
5. Clearances: 1" from combustible materials for vent pipes.

WARNING! Improper venting can cause carbon monoxide poisoning. Follow all clearance requirements.

Startup and Commissioning

Complete startup procedure to ensure proper operation.

1. Verify installations: Check all connections, clearances, and settings.
2. Power on: Restore electrical power to furnace.
3. Set thermostat: Call for heat and observe ignition sequence.
4. Check gas pressure: Verify manifold pressure at 3.5" WC.
5. Measure temperature rise: Ensure within 35-65°F range.
6. Check venting: Verify proper draft and combustion.
7. Test safety controls: Verify limit switch and pressure switch operation.

Tip: Use combustion analyzer to verify CO levels and combustion efficiency.

Maintenance

Regular maintenance ensures optimal performance and longevity.

Monthly: Check and replace air filter if dirty. Annual: Professional inspection including heat exchanger inspection, blower cleaning, and safety control testing.

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

Troubleshooting

Reset: Turn power off for 30 seconds to reset control board.

Service: 1-877-254-4729; www.goodmanmfg.com