Armstrong Furnace Repair Manual

The Armstrong Furnace is a high-efficiency heating system designed for residential and light commercial use, featuring advanced combustion technology, multiple heat exchanger stages, variable-speed blower motors, electronic ignition systems, and integrated safety controls. Below are key sections for safety procedures, technical specifications, troubleshooting, maintenance, and repair instructions.

1. Safety Precautions 2. System Overview 3. Installation Guidelines 4. Technical Specifications 5. Control System Operation 6. Electrical Connections 7. Gas System Components 8. Venting Requirements 9. Maintenance Procedures 10. Regulatory Compliance 11. Troubleshooting Guide

Safety Precautions

Critical safety measures for furnace operation and repair.

Safety ItemProcedure
Gas Valve ShutoffAlways turn off gas supply before servicing
Electrical DisconnectSwitch off power at service panel
Carbon Monoxide DetectionInstall CO detectors near furnace area
Venting InspectionCheck for blockages before operation
Combustion AirEnsure adequate fresh air supply
Heat Exchanger InspectionCheck for cracks annually
Flame ObservationVerify proper burner operation
Pressure TestingTest gas lines for leaks
Clearance RequirementsMaintain proper spacing from combustibles
Personal Protective EquipmentWear safety glasses and gloves

System Overview

Major components: Heat exchanger, burners, blower assembly, gas valve, ignition system, control board, limit switches, pressure switches.

  1. Heat Exchanger: Primary and secondary stages for maximum efficiency
  2. Burner Assembly: Stainless steel construction with precise air/fuel mixture
  3. Blower Motor: Variable-speed ECM motor for quiet operation
  4. Control System: Integrated furnace controller with diagnostic LEDs
  5. Venting System: PVC pipe for direct vent or conventional chimney

WARNING! Furnace contains high voltage and combustible gas. Only qualified technicians should perform repairs.

Installation Guidelines

Proper furnace installation ensures safe and efficient operation.

  1. Location Selection: Choose well-ventilated area with service clearance
  2. Combustion Air: Provide adequate fresh air supply per local codes
  3. Venting Installation: Follow manufacturer specifications for pipe size and routing
  4. Gas Connection: Use approved pipe compound and test for leaks
  5. Electrical Wiring: Connect to dedicated circuit with proper grounding
  6. Ductwork: Ensure proper sizing and sealing

CAUTION! Installation must comply with all local building codes and manufacturer specifications.

Technical Specifications

Control System Operation

Integrated furnace controller with diagnostic capabilities.

Control Board: Monitors safety devices, controls ignition sequence, manages blower operation, provides error codes via LED flash patterns.

Operation Sequence: Call for heat → Pressure switch check → Inducer motor start → Hot surface ignition → Gas valve opening → Flame verification → Blower activation → Normal operation → Satisfied call → Post-purge cycle.

Diagnostic Codes: LED flash patterns indicate specific fault conditions (1 flash = pressure switch, 2 flashes = ignition failure, etc.)

Electrical Connections

Proper wiring ensures safe and reliable furnace operation.

  1. Disconnect power at main service panel before wiring
  2. Connect 120V supply to designated terminals
  3. Install properly sized fuses or circuit breakers
  4. Connect thermostat wires to correct terminals (R, W, G, Y, C)
  5. Verify proper grounding of all components
  6. Check all electrical connections for tightness

Tip: Use voltage tester to confirm power is off before beginning electrical work.

Gas System Components

Gas train components and their functions.

  1. Manual Shutoff Valve: Allows gas supply isolation
  2. Gas Valve: Regulates gas flow and pressure
  3. Pressure Regulator: Maintains consistent gas pressure
  4. Burner Orifices: Control gas flow to individual burners
  5. Manifold Assembly: Distributes gas to all burners
  6. Combustion Chamber: Contains burner flames

WARNING! Always use leak detection solution to check for gas leaks after any gas system work.

Venting Requirements

Proper venting is critical for safe furnace operation.

Direct Vent Systems: Use approved PVC pipe materials, maintain proper slope for condensation drainage, follow manufacturer specifications for maximum vent length and number of elbows.

Conventional Venting: Ensure proper chimney condition, install draft hood correctly, verify adequate draft.

Maintenance Procedures

Regular maintenance ensures optimal furnace performance and longevity.

  1. Annual Inspection: Complete system check by qualified technician
  2. Filter Replacement: Change filters every 1-3 months
  3. Burner Cleaning: Remove and clean burners annually
  4. Heat Exchanger Inspection: Check for cracks or corrosion
  5. Blower Maintenance: Clean blower wheel and housing
  6. Venting Inspection: Check for blockages or damage
  7. Electrical Check: Verify tight connections and component operation

CAUTION! Only qualified personnel should perform furnace maintenance.

Regulatory Compliance

ANSI Z21.47: Certified for gas-fired central furnaces. UL 795: Commercial-industrial gas heating equipment. All installations must comply with National Fuel Gas Code (NFPA 54) and local building codes. For technical support, contact Armstrong Air Technical Services at 1-800-448-5872 or visit www.armstrongair.com.

Troubleshooting Guide

SymptomPossible CauseCorrective Action
Furnace won't startPower supply, thermostat, door switchCheck circuit breaker, verify thermostat setting, ensure door closed properly
No heatGas supply, ignition, limit switchVerify gas valve open, check for spark/flame, reset limit switch
Short cyclingDirty filter, blocked vent, overheatingReplace filter, clear vent obstructions, check airflow
Blower won't stopThermostat fan setting, control boardCheck thermostat fan setting, inspect control board relay
Unusual noisesLoose components, motor bearingsTighten all fasteners, lubricate or replace motor
Pilot outageDraft, thermocouple, gas pressureCheck venting, replace thermocouple, verify gas pressure
Error codes flashingVarious system faultsRefer to diagnostic chart in control section

Reset Procedure: Turn power off for 30 seconds, then restore power.

Service Contact: 1-800-448-5872; www.armstrongair.com

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