American Standard HVAC YHC120A Manual

The American Standard YHC120A is a high-efficiency residential gas furnace with 120,000 BTU input capacity, featuring a two-stage gas valve, variable-speed blower motor, durable aluminized steel heat exchanger, electronic ignition, integrated diagnostic controls, and compatibility with various thermostat systems. Designed for reliable heating performance with AFUE ratings up to 96.1%. Below are key sections for safety, features, installation, setup, operation, maintenance, and troubleshooting.

Features at a Glance

Key components: Two-stage gas valve, Variable-speed ECM blower motor, Aluminized steel primary heat exchanger, Stainless steel secondary heat exchanger, Integrated control board, Pressure switch, Flame sensor, Igniter, Filter rack.

Installation Requirements

Unpack and inspect unit for shipping damage. Verify location meets clearance requirements.

1. Location requirements: Minimum 24" front clearance, 6" sides, 6" rear, 24" above for service.
2. Venting: Use approved PVC pipe; maintain proper slope for condensate drainage.
3. Gas connection: Use black iron pipe; install sediment trap; pressure test for leaks.
4. Electrical: 120V AC, 60Hz dedicated circuit; proper grounding required.
5. Drain connection: Connect condensate drain to suitable drain or pump.

WARNING! Installation must comply with local codes and be performed by qualified HVAC technician. Gas furnaces can produce carbon monoxide.

First-Time Startup

Complete installation checks before applying power. Follow startup sequence carefully.

1. Verify all connections: Gas, electrical, venting, drain, and ductwork.
2. Install air filter: Ensure proper size and orientation.
3. Power on: Turn on electrical disconnect and gas supply.
4. Thermostat setup: Set to HEAT mode, temperature above room temp.
5. Observe ignition sequence: Control board LED will indicate status.
6. Check operation: Verify proper flame, airflow, and temperature rise.
7. Adjust blower speed: If required per installation manual.

CAUTION! Never bypass safety controls. Test carbon monoxide detectors after installation.

Specifications

• Model: YHC120A
• Input Capacity: 120,000 BTU/hr
• Output Capacity: Up to 115,200 BTU/hr
• AFUE Rating: Up to 96.1%
• Stages: Two-stage heating
• Blower Type: Variable-speed ECM
• Motor Speed: Adjustable via control board taps
• Electrical: 120V AC, 60Hz, 15A circuit
• Gas Type: Natural gas (convertible to LP with kit)
• Gas Pressure: 3.5" WC natural gas
• Vent Size: 2" or 3" PVC
• Dimensions: Varies by configuration
• Warranty: Limited lifetime heat exchanger, 10-year parts

Controls and Settings

Integrated control board with diagnostic LED. DIP switches for configuration.

Control Board LED Codes: Steady on = normal operation; 1 flash = pressure switch; 2 flashes = igniter failure; 3 flashes = flame sense; 4 flashes = limit switch; 5 flashes = rollout switch; 6 flashes = blower error; 7 flashes = gas valve error.

DIP Switch Settings: SW1-1: Blower delay; SW1-2: Continuous fan speed; SW1-3: Heating speed low; SW1-4: Heating speed high. Thermostat Connections: R (24V), C (Common), W1/W2 (Heat), G (Fan), Y1/Y2 (Cool if applicable).

Connecting Thermostat

Compatible with single-stage, two-stage, and programmable thermostats.

1. Turn off power at disconnect before wiring.
2. Match thermostat wires to control board terminals.
3. For two-stage operation: Connect W1 and W2.
4. For variable-speed control: Use communicating thermostat if equipped.
5. Secure connections and restore power.

Tip: Use 18-gauge thermostat wire. Follow thermostat manufacturer instructions for programming.

Operating Modes

Two-stage heating operation for improved comfort and efficiency.

1. Low-stage operation: Runs at approximately 65% capacity for mild conditions.
2. High-stage operation: Activates when heating demand exceeds low-stage capacity.
3. Fan modes: AUTO (cycles with heat), ON (continuous circulation).
4. Ignition sequence: Prepurge, igniter warm-up, gas valve opening, flame proving.
5. Shutdown sequence: Gas valve closes, post-purge blower operation.

WARNING! Do not attempt to adjust gas pressure without proper tools and training.

Maintenance Procedures

Annual maintenance recommended by qualified technician.

• Monthly: Check and replace air filter as needed.
• Annual: Inspect heat exchanger for cracks or corrosion.
• Annual: Clean flame sensor with fine sandpaper.
• Annual: Check vent system for obstructions.
• Annual: Verify gas pressure and combustion analysis.
• Annual: Lubricate inducer motor if required (non-sealed bearings).
• Annual: Check drain system for clogs.

Care & Cleaning

Turn off power before any cleaning. Keep area around furnace clear.

1. Exterior: Wipe with damp cloth; avoid water entry.
2. Burners: Vacuum if accessible during professional service.
3. Drain trap: Flush with water annually.
4. Condensate line: Clear with nitrogen or approved cleaner.

CAUTION! Never use flammable cleaners. Do not spray water into electrical components.

Regulatory Information

ANSI Z21.47/CSA 2.3: Certified for US and Canada. UL listed. Complies with Department of Energy efficiency standards. Manufactured by American Standard Heating & Air Conditioning, a division of Trane Technologies. For technical support, contact 1-800-926-9669 or visit www.americanstandardair.com. Serial number contains manufacture date (week/year).

Troubleshooting

Reset Procedure: Turn off power for 30 seconds, then restore. If problem persists, call for service.

Emergency Shutdown: Turn off gas valve at unit, turn off electrical disconnect, call qualified technician.

Service: 1-800-926-9669; www.americanstandardair.com