Coleman 7900 Series Furnace Manual

The Coleman 7900 Series Furnace is a high-efficiency gas furnace designed for residential heating applications. This series features advanced combustion technology, variable-speed blower motors, durable heat exchangers, electronic ignition systems, and comprehensive safety controls. Below are key sections for safety, features, installation, operation, maintenance, and troubleshooting.

Features at a Glance

Key components: High-efficiency heat exchanger, variable-speed blower motor, electronic ignition system, integrated control board, pressure switches, flame sensor, and safety shut-off valves.

Installation Requirements

Unpack and inspect all components. Ensure proper clearances and mounting surface.

1. Location: Install in approved locations with proper clearances (minimum 1" from combustible materials).
2. Venting: Install PVC vent pipes according to local codes and manufacturer specifications.
3. Gas Supply: Connect to proper gas line with sediment trap and shut-off valve.
4. Electrical: Connect to 120V AC power with proper grounding.
5. Ductwork: Ensure proper return and supply duct connections.

WARNING! Installation must be performed by qualified HVAC technician. Improper installation can cause fire, explosion, or carbon monoxide poisoning.

First-Time Setup

Power on furnace; follow startup sequence.

1. System check: Verify all connections are secure and gas supply is turned on.
2. Thermostat setup: Connect compatible thermostat and set to heating mode.
3. Initial startup: System will run through self-diagnostic and ignition sequence.
4. Airflow adjustment: Set blower speed for proper airflow and temperature rise.
5. Combustion analysis: Verify proper gas pressure and combustion efficiency.

CAUTION! Never bypass safety controls. Ensure proper ventilation during initial startup.

Specifications

• Heating Capacity: 40,000 to 120,000 BTU/hr (model dependent)
• Efficiency: Up to 96% AFUE
• Gas Type: Natural Gas or LP (conversion kit required)
• Electrical: 120V AC, 60Hz, 15 Amp circuit
• Blower Motor: Variable-speed ECM
• Airflow: 600 to 2000 CFM
• Venting: PVC pipe (2" or 3" depending on model)
• Operating Temp Range: -30°F to 150°F ambient
• Warranty: Limited lifetime heat exchanger, 10 years parts

Controls and Settings

Access control board via front panel. Integrated diagnostic LED for error codes.

Control Board: POWER switch, FAN control, SYSTEM reset, diagnostic LED.

Temperature: Controlled by external thermostat. Blower: Variable speed with multiple tap settings. Safety: Pressure switches, flame rollout switch, high limit switch. Diagnostic: LED flash codes for troubleshooting (1 flash = pressure switch, 2 flashes = ignition failure, etc.).

Venting and Combustion Air

PVC vent pipes required for proper operation. Separate combustion air intake recommended.

1. Vent piping: Use approved PVC pipe with proper slope and supports.
2. Termination: Locate vent terminals according to local codes (typically 12" above ground).
3. Combustion air: Ensure adequate fresh air supply for proper combustion.
4. Clearances: Maintain proper clearances from windows, doors, and air intakes.

Tip: Regular inspection of vent system is essential for safe operation.

Operation Instructions

Standard heating operation controlled by thermostat.

1. Thermostat call: Set thermostat to desired temperature above room temperature.
2. Ignition sequence: Inducer motor starts, pressure switch proves, igniter heats, gas valve opens.
3. Burner operation: Main burners ignite, flame sensor confirms, blower starts after delay.
4. Normal operation: System maintains set temperature with cycling.
5. Shutdown: Thermostat satisfied, gas valve closes, blower continues for post-purge.

WARNING! Never operate furnace without proper venting and combustion air. Carbon monoxide hazard.

Maintenance Procedures

Regular maintenance required for optimal performance and safety.

1. Monthly: Check and replace air filter as needed.
2. Annual: Professional inspection and cleaning.
3. Burner cleaning: Remove and clean burners annually.
4. Heat exchanger: Visual inspection for cracks or damage.
5. Blower assembly: Clean blower wheel and housing.
6. Vent system: Inspect for obstructions or damage.

CAUTION! Disconnect power before performing any maintenance. Only qualified technicians should service gas components.

Safety Features

Multiple safety systems: Flame rollout switch, high limit switch, pressure switches, flame sensor, gas valve safety shut-off.

Regulatory Information

ANSI Z21.47: Certified for natural gas and LP operation. UL listed. Meets all applicable safety standards. For support, visit www.colemanac.com or contact 1-800-426-5362. Installation must comply with local building codes and NFPA 54.

Troubleshooting

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

Service: 1-800-426-5362; www.colemanac.com