American Standard HVAC ALLEGIANCE 2A7A4 Manual

The American Standard ALLEGIANCE 2A7A4 is a high-efficiency residential gas furnace designed for reliable heating performance. It features a durable heat exchanger, multi-speed blower motor, electronic ignition, integrated control board with diagnostic LED, and compatibility with various thermostat systems. Below are key sections for safety, features, installation, setup, operation, maintenance, and troubleshooting.

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

Features at a Glance

Key components: Durable aluminized steel heat exchanger, multi-speed direct-drive blower motor, hot surface igniter, integrated control board with diagnostic LED, pressure switch, flame sensor, and filter rack.

FeatureDescription
Heat ExchangerAluminized steel construction for durability and efficiency
Blower MotorMulti-speed direct-drive for adjustable airflow
Ignition SystemHot surface igniter for reliable lighting
Control BoardIntegrated with diagnostic LED for error codes
Pressure SwitchEnsures proper venting before ignition
Flame SensorMonitors burner flame for safety
Filter RackStandard 1-inch filter slot (optional media filter compatible)
Gas ValveAdjustable for natural or propane gas (conversion kit required)
Vent ConnectionsPVC vent compatible (side or top)
Electrical120V AC, 60Hz power supply

Installation Requirements

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

  1. Location: Install in level, indoor space with minimum clearances (0" sides, 1" front, 0" rear, 1" top).
  2. Venting: Use approved PVC pipe for intake and exhaust; maintain slope away from furnace.
  3. Gas Supply: Connect to gas line with shutoff valve; pressure test for leaks.
  4. Electrical: Connect 120V power with dedicated circuit; ground properly.
  5. Ductwork: Attach supply and return plenums; seal joints.

WARNING! Installation must comply with local codes and be performed by qualified technician. Gas leaks can cause explosion.

First-Time Setup & Startup

After installation, perform startup sequence.

  1. Set thermostat: Turn to OFF position; set to HEAT mode after startup.
  2. Power on: Turn furnace power switch ON; control board LED will blink.
  3. Check gas: Ensure gas valve is open; verify pressure (natural gas: 3.5" WC).
  4. Startup: Set thermostat above room temp; furnace should ignite within 60 seconds.
  5. Verify operation: Listen for proper ignition; check airflow from vents.

CAUTION! Do not bypass safety devices. If furnace fails to start, refer to troubleshooting.

Specifications

Controls and Settings

Access control board behind lower access panel. LED flashes codes for status/errors.

Thermostat: Use compatible 24V thermostat (1-stage heat, 1-stage cool if AC connected).

Blower Speeds: Adjust via motor taps (HEAT: tap 3-4, COOL: tap 4-5). Gas Pressure: Adjust at gas valve (natural gas: 3.5" WC). Limit Switch: Auto-reset if overheated. Diagnostic Codes: 1 flash = normal, 2 flashes = pressure switch, 3 flashes = ignition lockout, etc. (see label).

Connecting Thermostat & Power

Thermostat: Use 18-gauge wire; connect R (24V), W (heat), G (fan), C (common). Power: 120V dedicated circuit.

  1. Turn off power at furnace and breaker.
  2. Remove access panel; locate terminal block.
  3. Connect thermostat wires to corresponding terminals.
  4. Connect 120V power leads (black-hot, white-neutral, green-ground).
  5. Restore power; verify operation.

Tip: Label wires before disconnecting. Ensure polarity is correct.

Operating Instructions

For normal heating operation.

  1. Set thermostat to HEAT mode and desired temperature.
  2. Furnace will initiate sequence: blower prepurge, igniter warm-up, gas valve open, ignition.
  3. Once flame detected, blower starts after heat exchanger warm-up delay.
  4. When thermostat satisfied, gas valve closes; blower runs post-purge then stops.
  5. Continuous fan: Set thermostat to FAN ON for constant airflow.

WARNING! Do not adjust thermostat frequently; allow cycles to complete. Strange odors on first use are normal.

Maintenance Procedures

Annual maintenance recommended. Turn off power and gas before servicing.

  1. Filter: Replace 1" filter every 1-3 months; check monthly during heavy use.
  2. Blower: Vacuum blower wheel and motor annually; ensure it spins freely.
  3. Flame Sensor: Clean with fine sandpaper or steel wool yearly.
  4. Vents: Inspect PVC vents for obstructions or damage.
  5. Drainage: Check condensate drain line and trap; clear if clogged.

Care & Cleaning

Keep area around furnace clear of debris and flammable materials. Clean exterior with dry cloth.

CAUTION! Do not use water or cleaners on electrical components. Keep filter clean to maintain efficiency.

Regulatory Information

Complies with ANSI Z21.47/CSA 2.3 standards for gas-fired furnaces. UL listed. Manufactured to meet U.S. Department of Energy efficiency standards. For support, contact American Standard Customer Service at 1-800-926-9663 or visit www.americanstandardair.com.

Troubleshooting

SymptomPossible CauseCorrective Action
No heatThermostat, power, gasCheck thermostat setting; verify power and gas valve on; check filter.
Blower not runningPower, motor, limit switchEnsure power on; check for tripped breaker; reset limit switch if overheated.
Furnace short cyclesDirty filter, blocked ventReplace filter; check vents for obstructions.
Ignition failureGas supply, igniter, sensorVerify gas pressure; inspect igniter for cracks; clean flame sensor.
Error code flashesSee control board LEDCount flashes; refer to label on access panel for code meaning.

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

Service: 1-800-926-9663; www.americanstandardair.com

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