Carrier 2 Stage Furnace Manual

The Carrier 2 Stage Furnace is a high-efficiency heating system featuring two-stage gas operation, variable-speed blower motor, electronic ignition, built-in diagnostics, compatibility with thermostats, safety shutoff, filter monitoring, and quiet operation. Designed for residential use with natural gas or propane, it offers energy-efficient heating with AFUE ratings up to 98%. Below are key sections for safety, features, installation, setup, operation, maintenance, and troubleshooting.

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

Features at a Glance

Key components: Two-stage gas valve, variable-speed blower, heat exchanger, control board, filter access, pressure switches, ignition system, flue outlet.

Feature	Description
Two-stage operation	Low and high fire stages for efficient heating
Variable-speed blower	Adjusts airflow for comfort and efficiency
Electronic ignition	Hot surface igniter for reliable startup
Diagnostic LED	Flashing codes for error identification
Filter monitor	Reminds when to replace air filter
Safety shutoff	Automatic shutdown if issues detected
Quiet operation	Insulated cabinet and variable-speed motor
Thermostat compatibility	Works with single-stage and two-stage thermostats
Gas type	Natural gas or propane (field convertible)
Venting	PVC pipe for direct vent or conventional

Installation

Unpack and inspect contents. Ensure proper location with clearances.

Position furnace: Place on level surface in well-ventilated area.
Connect gas line: Use black iron pipe with approved fittings.
Connect electrical: 120V AC power supply and thermostat wiring.
Install venting: Use PVC pipe for intake and exhaust.
Connect ductwork: Secure supply and return air ducts.

WARNING! Installation must be performed by qualified technician. Follow all local codes. Ensure proper combustion air and venting.

First-Time Setup

Power on furnace; follow startup procedure.

Verify gas connection: Check for leaks with soap solution.
Set gas type: Configure for natural gas or propane.
Connect thermostat: Wire compatible two-stage thermostat.
Test operation: Run through heating cycle.
Adjust blower speed: Set for proper airflow.

CAUTION! Never bypass safety controls. Ensure proper ventilation before operation.

Specifications

Heating Capacity: 40,000 to 120,000 BTU/h (model dependent).
Stages: 2 (low/high fire).
AFUE: Up to 98% efficiency.
Blower Motor: Variable-speed ECM.
Ignition: Hot surface electronic.
Voltage: 120V AC, 60Hz.
Gas Pressure: Natural gas: 3.5" WC; Propane: 10" WC.
Venting: 2" PVC pipe (intake/exhaust).
Sound Level: As low as 65 dBA.

Controls and Settings

Access controls via integrated control board. Front Panel: Power switch, diagnostic LED, service switch.

Thermostat: Heat mode, fan control, temperature setpoint, system switch.

Operation: Two-stage heating (low stage for mild weather, high stage for cold). Blower: Variable speeds for heating and continuous fan. Diagnostics: LED flash codes for error diagnosis. Settings: Blower speed, gas pressure, temperature rise.

Connecting Thermostat

Compatible with single-stage and two-stage thermostats. Wiring: R, C, W1, W2, G, Y.

Turn off power to furnace.
Connect thermostat wires to control board terminals.
For two-stage: Connect W1 and W2.
Restore power and test operation.

Tip: Use thermostat with two-stage capability for optimal efficiency.

Operation Modes

Supports heating and fan-only operation.

Heating mode: Thermostat calls for heat, furnace ignites in low or high stage.
Fan mode: Continuous or auto operation.
Staging: Low fire for small heat demand, high fire for large demand.
Shutdown: Automatic when thermostat satisfied or fault detected.

WARNING! Do not operate without proper venting. Monitor for unusual noises or odors.

Maintenance Procedures

Regular maintenance ensures efficiency and longevity.

Monthly: Check and replace air filter as needed.
Annual: Professional inspection and cleaning.
Blower: Clean blower assembly and motor.
Heat exchanger: Inspect for cracks or corrosion.
Venting: Check for obstructions in PVC pipes.

CAUTION! Always turn off power and gas before servicing.

Safety Features

Flame rollout switch: Shuts off gas if flame escapes burner. Limit switch: Prevents overheating. Pressure switch: Ensures proper venting. Ignition control: Safely manages gas valve and igniter.

Regulatory Information

ANSI Z21.47: Certified for safety and performance. UL listed. Complies with U.S. energy efficiency standards. Copyright © Carrier Corporation; trademarks of Carrier Global Corporation. For support, visit www.carrier.com or contact 1-800-CARRIER.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Furnace won't start	Power/thermostat	Check circuit breaker; verify thermostat settings; ensure door closed.
No heat	Gas supply/ignition	Verify gas valve on; check for ignition failure; inspect filter.
Short cycling	Filter/venting	Replace dirty filter; check for blocked vent; verify thermostat location.
Blower not working	Motor/control	Check blower door switch; inspect motor; verify thermostat fan setting.
Error code flashing	System fault	Refer to diagnostic chart in manual; reset if safe.

Reset: Turn power off for 30 seconds then restore.

Service: 1-800-CARRIER; www.carrier.com