American Standard 90 Furnace Installation Manual

The American Standard 90 Furnace is a high-efficiency gas furnace designed for residential heating applications, featuring AFUE ratings up to 90%, variable-speed blower motor, durable heat exchanger, multi-speed operation, electronic ignition, built-in diagnostic system, safety controls, and compatibility with various thermostat systems. Below are key sections for safety, features, installation, setup, operation, and troubleshooting.

Features at a Glance

Key components: High-efficiency heat exchanger, variable-speed blower, electronic ignition system, pressure switches, flame sensor, gas valve, control board, and diagnostic LED.

Installation Requirements

Verify local codes and obtain necessary permits before installation.

1. Location: Install in approved locations only - utility rooms, basements, or closets with proper clearances.
2. Clearances: Minimum 1-inch from combustible materials, 24-inch service clearance in front.
3. Combustion Air: Ensure adequate combustion and ventilation air supply.
4. Electrical: 120V, 60Hz dedicated circuit required.
5. Gas Supply: Proper gas line sizing and pressure requirements.

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

Step-by-Step Installation

Follow these steps in sequence for proper installation.

1. Position furnace: Place on level surface or install hanging brackets.
2. Connect ductwork: Attach supply and return ducts securely.
3. Install vent pipes: Use approved PVC materials for intake and exhaust.
4. Connect gas line: Use black iron pipe with proper thread sealant.
5. Wire electrical: Connect line voltage and thermostat wiring.
6. Install condensate drain: Route to approved drain location.
7. Install air filter: Ensure proper filter size and orientation.

CAUTION! Always test for gas leaks using bubble solution. Never use open flame.

Specifications

• AFUE Rating: Up to 90% Annual Fuel Utilization Efficiency
• Input BTU/H: 40,000 - 120,000 (model dependent)
• Gas Type: Natural Gas or LP (with conversion kit)
• Electrical: 120V AC, 60Hz, 15 Amp circuit
• Blower Motor: Variable-speed ECM
• Stages: Single-stage or two-stage operation
• Venting: PVC pipe (2-inch or 3-inch)
• Sound Level: As low as 65 dB
• Warranty: 20-year heat exchanger, 5-year parts

Controls and Settings

Access control board via front panel. Diagnostic LED provides status codes.

Control Board: POWER switch, FUSE, LED status light, DIP switches for configuration.

DIP Switch Settings: Heat staging, blower delays, thermostat type. Gas Valve: Manual shutoff, pressure test ports. Blower Speeds: Adjustable for heating and continuous fan modes. Limit Switches: Automatic high-temperature protection.

Electrical Connections

120V power supply and low-voltage thermostat connections.

1. Disconnect power at main breaker before wiring.
2. Connect line voltage: Black (hot), White (neutral), Green (ground).
3. Connect thermostat: R (24V power), W (heat), G (fan), C (common).
4. Verify proper grounding and polarities.

Tip: Use wire nuts and electrical tape for secure connections.

Gas Line Connections

Natural gas or LP connections with proper sizing and pressure.

1. Install sediment trap before gas valve connection.
2. Use pipe dope or Teflon tape on threaded connections.
3. Pressure test: Natural gas - 7-inch WC, LP gas - 11-inch WC.
4. Check for leaks with bubble solution.
5. Connect flexible gas connector if required by local codes.

WARNING! Gas connections must be pressure tested and leak-checked before operation.

Venting System

PVC vent pipes for intake and exhaust.

1. Use Schedule 40 PVC pipe for venting.
2. Maintain proper slope: 1/4-inch per foot toward furnace.
3. Maximum vent length: Consult installation guide for specific model.
4. Install termination caps properly - 12 inches minimum from ground.
5. Secure all joints with PVC cement.

CAUTION! Vent pipes must be properly supported and protected from damage.

Startup and Commissioning

Initial startup procedure and system verification.

1. Verify all connections are secure and proper.
2. Restore electrical power and gas supply.
3. Set thermostat to heat mode above room temperature.
4. Observe ignition sequence: Inducer motor, hot surface igniter, gas valve, flame.
5. Check temperature rise: 35-65°F across heat exchanger.
6. Measure gas pressure: Adjust if necessary.
7. Verify proper vent operation and condensate drainage.

WARNING! Monitor first complete heating cycle for proper operation.

Maintenance Guidelines

Regular maintenance ensures optimal performance and longevity.

Monthly: Check and replace air filter as needed. Annual: Professional inspection and cleaning. Components to service: Heat exchanger, burners, blower assembly, drain system, vent pipes.

CAUTION! Always disconnect power before performing any maintenance.

Troubleshooting

Reset: Power cycle furnace by turning off/on at disconnect or breaker.

Service: 1-800-american; www.americanstandard.com