Carrier 90 Furnace Installation Manual

The Carrier 90 Furnace is a high-efficiency gas furnace designed for residential heating applications. This model features advanced combustion technology, variable-speed blower motor, durable heat exchanger construction, electronic ignition system, multiple-speed airflow adjustment, integrated diagnostic controls, and compatibility with various thermostat systems. Below are key sections for safety, installation procedures, electrical connections, gas line connections, ventilation requirements, startup procedures, 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, gas valve, and diagnostic LED indicators.

Safety Precautions

Read all instructions before beginning installation. Follow local codes and regulations.

1. Turn off electrical power and gas supply before installation.
2. Wear appropriate personal protective equipment (safety glasses, gloves).
3. Ensure proper clearance from combustible materials.
4. Verify adequate combustion air and ventilation.
5. Check for gas leaks using approved leak detection solution.

WARNING! Failure to follow safety precautions may result in fire, explosion, carbon monoxide poisoning, or personal injury. Installation must be performed by qualified HVAC technician.

Pre-Installation Requirements

Verify site conditions and gather necessary tools and materials before beginning installation.

1. Location: Indoor installation only, protected from weather and moisture.
2. Clearance: Minimum 1-inch clearance from combustible materials on all sides.
3. Floor: Level, solid surface capable of supporting furnace weight.
4. Gas Supply: Adequate gas pressure and pipe sizing for furnace requirements.
5. Electrical: Dedicated 120V AC circuit with proper grounding.
6. Venting: Proper vent pipe materials and routing per local codes.

CAUTION! Furnace is heavy; use proper lifting techniques and equipment.

Specifications

• Input Capacity: 60,000 - 120,000 BTU/H (model dependent)
• Efficiency: 90% AFUE minimum
• Gas Type: Natural gas or LP (conversion kit required)
• Gas Pressure: Natural gas: 3.5" WC; LP: 10" WC
• Electrical: 120V AC, 60Hz, 15A circuit
• Blower Motor: Variable-speed ECM, 1/3 - 3/4 HP
• Airflow: 800 - 2000 CFM (configurable)
• Venting: PVC or CPVC pipe (2" minimum diameter)
• Dimensions: Varies by model (check specific model data)
• Weight: 120 - 180 lbs (depending on model)

Installation Procedures

Follow these steps for proper furnace installation and positioning.

1. Position furnace: Place in approved location with proper clearances.
2. Level unit: Use shims if necessary to ensure level installation.
3. Duct connections: Connect supply and return ducts using approved methods.
4. Gas line: Connect gas supply line using approved pipe and fittings.
5. Electrical: Connect power supply and thermostat wiring.
6. Venting: Install intake and exhaust vent pipes per code requirements.
7. Condensate: Connect condensate drain line with proper trap.

Tip: Verify all connections are secure and properly sealed before startup.

Electrical Connections

Proper electrical connections are critical for safe and reliable operation.

1. Disconnect power at main electrical panel before making connections.
2. Connect line voltage: Black (hot), white (neutral), green (ground) to furnace terminal block.
3. Connect low voltage: R (24V hot), W (heat), G (fan), C (common) to thermostat terminals.
4. Verify proper grounding of all electrical components.
5. Install appropriate fuse or circuit breaker for furnace protection.

WARNING! Electrical work must comply with NEC and local codes. Use copper conductors only.

Gas Line Connections

Gas line installation requires careful attention to safety and code compliance.

1. Shut off gas supply at main valve before beginning work.
2. Use approved black iron pipe or CSST for gas line installation.
3. Apply pipe thread sealant suitable for gas service to all connections.
4. Install sediment trap before gas valve connection.
5. Connect flexible gas connector if required by local codes.
6. Pressure test: Test gas line at 14" WC for 10 minutes with no pressure drop.
7. Check for leaks using approved leak detection solution.

CAUTION! Never use matches or open flame to check for gas leaks.

Venting System

Proper venting is essential for safe operation and efficiency.

1. Use only PVC or CPVC pipe approved for furnace venting.
2. Maintain minimum 1/4" per foot slope toward furnace for condensate drainage.
3. Keep vent runs as short and straight as possible.
4. Install termination caps at proper clearances from windows, doors, and air intakes.
5. Secure all joints with approved PVC cement.
6. Verify intake and exhaust pipes are properly separated at termination.

WARNING! Improper venting can cause carbon monoxide buildup and system failure.

Startup and Commissioning

Follow these procedures for initial startup and system verification.

1. Verify all installation steps are complete and connections are secure.
2. Restore electrical power and gas supply to furnace.
3. Set thermostat to call for heat and observe startup sequence.
4. Check gas pressure at manifold with manometer.
5. Verify proper flame characteristics and combustion.
6. Measure temperature rise across heat exchanger.
7. Check vent system for proper operation and draft.
8. Program thermostat settings and verify system operation.

CAUTION! Monitor system closely during first heating cycle for any abnormalities.

Maintenance Guidelines

Regular maintenance ensures optimal performance and longevity.

• Monthly: Check and replace air filter as needed
• Annual: Professional inspection and cleaning
• Seasonal: Verify proper system operation before heating season
• As needed: Clean flame sensor and burners
• Periodic: Check condensate drain system for blockages

WARNING! Only qualified technicians should perform internal component maintenance.

Troubleshooting

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

Service: Contact qualified HVAC technician for all service needs. Carrier support: 1-800-CARRIER