Century Gas Furnace Manual

The Century Gas Furnace is a high-efficiency residential heating system designed for reliable performance and energy savings. This manual covers installation, operation, maintenance, and troubleshooting for various Century furnace models. Below are key sections for safety, features, installation, setup, operation, and troubleshooting.

1. Features at a Glance 2. Installation 3. First-Time Setup 4. Specifications 5. Controls and Settings 6. Connecting Components 7. Operating Procedures 8. Safety Features 9. Maintenance & Cleaning 10. Regulatory Information 11. Troubleshooting

Features at a Glance

Key components: Gas valve, heat exchanger, blower motor, ignition system, thermostat connection, pressure switches, limit switches.

Feature	Description
Gas valve	Controls gas flow to burners
Heat exchanger	Transfers heat from combustion to air
Blower motor	Circulates heated air through ductwork
Ignition system	Hot surface or intermittent pilot ignition
Thermostat connection	For temperature control input
Pressure switches	Ensures proper venting operation
Limit switches	Prevents overheating
POWER switch	Turns furnace on/off
Pilot light/igniter	Ignites gas for combustion
Filter access	For air filter replacement

Installation

Unpack and inspect contents. Ensure proper location with adequate clearance.

Gas line connection: Use approved gas piping; test for leaks with soap solution.
Electrical connection: Connect to 120V AC power supply with proper grounding.
Vent system: Install according to local codes; ensure proper draft.
Thermostat wiring: Connect to R, W, G terminals as required.
Ductwork: Connect supply and return ducts securely.

WARNING! Gas appliances can be dangerous; professional installation recommended. Ensure proper ventilation.

First-Time Setup

Power on furnace; follow startup sequence.

Gas supply: Ensure gas valve is open; check for leaks.
Thermostat setup: Set to HEAT mode; adjust temperature setting.
Initial ignition: System will attempt ignition sequence automatically.
Blower operation: Verify proper air circulation through vents.
Temperature calibration: Adjust thermostat if needed.

CAUTION! Do not bypass safety devices. If furnace fails to start, turn off and consult professional.

Specifications

Fuel Type: Natural gas or propane
Input BTU: 40,000-120,000 BTU/hr depending on model
Efficiency: 80-96% AFUE
Electrical: 120V AC, 60Hz
Blower Type: Multi-speed direct drive
Vent Size: 3-5 inch PVC or metal depending on model
Filter Size: Standard 16x20x1 inch or model-specific
Operating Temp: Standard indoor conditions
Warranty: 5-20 years on heat exchanger

Controls and Settings

Access control board via front panel. Main switch: POWER ON/OFF.

Thermostat: HEAT/COOL/OFF, FAN AUTO/ON, temperature setting, system reset.

Control Board: Status lights (green=normal, red=fault), reset button, diagnostic codes. Gas Valve: Pressure adjustment, manual shutoff. Blower Control: Speed settings, delay timers. Limit Controls: High limit reset, rollout switch reset.

Connecting Components

Gas line: Black iron pipe with sediment trap. Electrical: 120V circuit with disconnect. Thermostat: 2-5 wire connection. Vent: PVC or metal piping.

Turn off gas and electrical power before connecting.
Match wire colors to terminal designations (R=24V, W=Heat, G=Fan).
Ensure all connections are tight and secure.
Test operation after connections complete.

Tip: Use pipe dope or Teflon tape on gas connections; never on flare fittings.

Operating Procedures

Normal heating cycle operation.

Thermostat call: Set thermostat above room temperature.
Ignition sequence: Inducer motor starts, pressure switch proves, igniter heats, gas valve opens.
Burner operation: Flame sensor confirms ignition, main burners fire.
Blower operation: Blower starts after heat exchanger warms up.
Cycle completion: Thermostat satisfied, gas valve closes, blower continues for cool-down.
Fan control: AUTO mode cycles with heat call; ON runs continuously.

WARNING! Never operate without filter. Keep combustibles away from furnace.

Safety Features

Flame Rollout Switch: Shuts off gas if flame rolls out of burner compartment. High Limit Switch: Prevents overheating. Pressure Switches: Ensure proper venting. Flame Sensor: Confirms burner ignition. Gas Valve: Automatic shutoff if ignition fails.

Maintenance & Cleaning

Turn off power and gas before maintenance. Replace filter monthly during heating season. Clean burners and heat exchanger annually. Check vent system for obstructions.

CAUTION! Carbon monoxide hazard - ensure proper venting. Use only manufacturer-approved parts.

Regulatory Information

ANSI Z21.47: Certified for gas-fired central furnaces. UL 795: Commercial-industrial gas heating equipment. Local codes may apply. For support, contact Century Customer Service at 1-800-722-1343 or visit www.centuryheating.com. Installation must comply with National Fuel Gas Code NFPA 54.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Furnace won't start	Power/gas/thermostat	Check circuit breaker, gas valve, thermostat setting and batteries.
No heat	Ignition/pilot	Check for spark at igniter; ensure gas supply; reset rollout switches.
Blower doesn't run	Motor/control	Check blower door switch; test motor capacitor; verify control board output.
Short cycling	Filter/limit switch	Replace dirty filter; check high limit switch; ensure proper airflow.
Strange odors	Dust/burning	Normal dust burn-off on first startup; if persistent, check for overheating.

Reset: Turn power off for 30 seconds then restart.

Service: 1-800-722-1343; www.centuryheating.com