Armstrong Air Furnace Service Manual

The Armstrong Air Furnace is a high-efficiency residential heating system designed for reliable performance and energy savings. This service manual covers installation, maintenance, troubleshooting, and repair procedures for certified HVAC technicians. Below are key sections for safety protocols, technical specifications, installation guidelines, operational procedures, maintenance schedules, and troubleshooting guides.

1. Safety Precautions 2. Technical Specifications 3. Installation Procedures 4. System Components 5. Electrical Wiring 6. Gas Line Connections 7. Venting Requirements 8. Startup and Commissioning 9. Maintenance Schedule 10. Troubleshooting Guide 11. Parts List and Diagrams

Safety Precautions

Critical safety information for installation and service technicians.

Hazard	Precaution
Electrical Shock	Disconnect power before servicing; use lockout/tagout procedures
Gas Leaks	Check all connections with leak detection solution; never use open flame
Carbon Monoxide	Ensure proper venting; test with CO detector after installation
High Temperature	Allow unit to cool before handling heat exchanger components
Moving Parts	Disconnect power before servicing blower motor or inducer assembly

Technical Specifications

Model Series: A95US1V, A80US1V, A70US1V
Input Capacity: 40,000 - 120,000 BTU/H
Efficiency Rating: 80% - 96% AFUE
Voltage Requirements: 120V AC, 60Hz
Gas Type: Natural Gas or LP (conversion kit required)
Maximum Gas Pressure: 14" W.C. Natural Gas, 14" W.C. LP
Minimum Gas Pressure: 5" W.C. Natural Gas, 11" W.C. LP
Vent Size: 2" - 6" PVC/CPVC depending on model
Operating Temp Range: -30°F to 120°F ambient

Installation Procedures

Proper installation ensures optimal performance and safety.

Location Selection: Install in clean, dry area with adequate combustion air and service clearance
Combustion Air: Ensure adequate fresh air supply per local codes
Leveling: Unit must be level within 1/4" for proper condensate drainage
Clearances: Maintain minimum clearances to combustibles as specified on unit rating plate
Ductwork: Size ductwork according to Manual J calculations

WARNING! Installation must comply with all local codes and manufacturer specifications. Only qualified technicians should perform installation.

System Components

Key furnace components and their functions.

Component	Function
Heat Exchanger	Transfers heat from combustion gases to air stream
Blower Assembly	Circulates air through duct system
Gas Valve	Regulates gas flow to burners
Inducer Motor	Removes combustion gases through vent system
Control Board	Manages system operation and safety controls
Ignition System	Hot surface igniter for reliable lighting
Pressure Switches	Verify proper venting and air flow
Limit Switches	Prevent overheating

Electrical Wiring

Proper electrical connections are critical for safe operation.

Power Supply: Connect to dedicated 15-amp circuit with proper grounding
Thermostat Wiring: Standard 5-wire connection (R, W, Y, G, C)
Humidifier: Optional 24VAC connection available
Safety Circuits: All safety devices must be properly connected and tested
Grounding: Ensure proper equipment grounding per NEC requirements

CAUTION! Always verify power is disconnected before making electrical connections.

Gas Line Connections

Gas piping must be properly sized and installed.

Pipe Sizing: Size gas line according to length and BTU requirements
Shut-off Valve: Install approved gas cock within 6 feet of unit
Drip Leg: Install sediment trap before gas connection
Pressure Test: Test entire gas system at 14" W.C. for 10 minutes
Leak Check: Test all connections with approved leak detection solution

WARNING! Gas connections must be made by qualified technician in accordance with local codes.

Venting Requirements

Proper venting is essential for safe operation and efficiency.

Material: PVC, CPVC, or ABS as approved by local codes
Slope: 1/4" per foot back to furnace for condensate drainage
Termination: Minimum 12" above ground level, 3 feet from openings
Clearances: Maintain required clearances to combustibles
Support: Support vent pipes every 4 feet horizontally

Startup and Commissioning

System startup procedure for certified technicians.

Visual Inspection: Verify all components are properly installed
Electrical Check: Verify proper voltage and grounding
Gas Pressure: Set manifold pressure to specifications on rating plate
Combustion Analysis: Verify CO levels and combustion efficiency
Airflow: Set blower speed for proper temperature rise
Safety Test: Verify all safety controls function properly
Customer Education: Explain operation and maintenance requirements

Maintenance Schedule

Recommended maintenance for optimal performance.

Interval	Maintenance Task
Monthly	Check air filter; replace if dirty
Annually	Professional inspection and cleaning
Heating Season	Test safety controls and thermostat operation
Every 3-5 Years	Complete system cleaning and component inspection

Troubleshooting Guide

Symptom	Possible Cause	Corrective Action
No heat	Thermostat, power, gas valve	Check thermostat setting; verify power; test gas valve operation
Short cycling	Dirty filter, limit switch	Replace filter; check airflow; test limit switch
Blower not running	Motor, capacitor, control board	Test motor windings; check capacitor; verify control board output
Gas valve not opening	Pressure switch, ignition	Verify pressure switch closure; check hot surface igniter
Condensate backup	Drain line blockage	Clear condensate line; check trap; verify proper slope

Parts List and Diagrams

Common replacement parts and exploded views available through authorized Armstrong distributors.

Heat Exchanger Assembly
Blower Motor and Wheel
Gas Valve Assembly
Control Board
Inducer Motor Assembly
Hot Surface Igniter
Flame Sensor
Pressure Switches
Limit Controls

Technical Support: 1-888-ARMSTRONG; www.armstrongair.com