Armstrong Gas Furnace Installation Manual

The Armstrong Gas Furnace is a high-efficiency heating system designed for residential use, featuring advanced combustion technology, multiple venting options, variable-speed blower motor, electronic ignition system, built-in diagnostic controls, safety shut-off features, and compatibility with various thermostat systems. Below are key sections for safety, installation procedures, electrical connections, gas line setup, venting requirements, startup procedures, and troubleshooting.

1. Safety Precautions 2. Pre-Installation Checklist 3. Installation Requirements 4. Technical Specifications 5. Step-by-Step Installation 6. Electrical Connections 7. Gas Line Installation 8. Venting System Setup 9. Startup & Commissioning 10. Maintenance Guidelines 11. Troubleshooting

Safety Precautions

Critical safety information for proper furnace installation and operation.

Hazard	Precaution
Gas Leaks	Check all connections with leak detection solution; never use open flame
Electrical Shock	Disconnect power before servicing; follow local electrical codes
Carbon Monoxide	Ensure proper venting; install CO detectors in living areas
Fire Hazard	Maintain clearances to combustibles as specified
Burn Risk	Allow furnace to cool before handling components
Explosion Risk	Never attempt to relight pilot if gas odor is present

Pre-Installation Checklist

Verify all requirements before beginning installation.

Check local codes: Ensure compliance with building, mechanical, and gas codes.
Inspect unit: Verify no shipping damage and all components present.
Location requirements: Confirm adequate space for service clearances.
Venting path: Plan vent and combustion air routing.
Gas supply: Verify adequate gas pressure and pipe sizing.
Electrical: Confirm proper voltage and dedicated circuit availability.

WARNING! Installation by qualified HVAC technician required. Improper installation may create hazardous conditions.

Installation Requirements

Minimum requirements for proper furnace installation.

Clearances: 1" sides, 1" rear, 6" front, 24" above
Gas Supply: 1/2" minimum pipe size, 7" WC pressure
Electrical: 120V, 60Hz, 15A dedicated circuit
Venting: Category IV approved PVC or CPVC
Combustion Air: Separate intake required for confined spaces
Drain Line: 3/4" PVC for condensate removal

Technical Specifications

Model Series: A95, A97, A98
Input BTU/H: 40,000 - 120,000
AFUE Rating: 95% - 98.5%
Blower Motor: Variable Speed ECM
Stages: Single or Two-Stage operation
Venting: Category IV (2-pipe system)
Gas Type: Natural Gas (convertible to LP)
Voltage: 120V/1Ph/60Hz
Dimensions: Varies by model (check specific model label)

Step-by-Step Installation

Complete installation procedure in proper sequence.

Position furnace: Place on level surface or install hanging brackets.
Connect ductwork: Attach supply and return ducts securely.
Install venting: Route PVC pipes per manufacturer specifications.
Connect gas line: Use approved pipe thread compound on all joints.
Wire electrical: Connect line voltage and thermostat wiring.
Install drain line: Route condensate to approved drain location.
Final checks: Verify all connections and clearances.

CAUTION! Never operate furnace without proper venting installed and secured.

Electrical Connections

Proper wiring procedures for safe operation.

Disconnect power: Turn off circuit breaker before beginning.
Line voltage: Connect black (hot), white (neutral), green (ground) wires.
Thermostat: Connect R, W, G, Y, C terminals as required.
Humidifier: Connect to HUM terminals if equipped.
Safety switches: Install door switch and high-limit controls.

Tip: Use wire nuts and electrical tape for all connections; follow NEC codes.

Gas Line Installation

Gas connection procedures and safety checks.

Shut off gas: Turn gas valve to OFF position at meter.
Pipe sizing: Use minimum 1/2" black iron pipe for runs under 30 feet.
Joint preparation: Apply pipe dope to male threads only.
Install sediment trap: Include drip leg before gas valve.
Pressure test: Test at 14" WC for 10 minutes with no drop.
Leak check: Use soap solution on all joints; watch for bubbles.

WARNING! Never use Teflon tape on gas line connections as shreds can clog orifices.

Venting System Setup

Category IV venting requirements and installation.

Material: Use only PVC, CPVC, or ABS approved for Category IV.
Slope: Vent pipe must slope downward 1/4" per foot toward furnace.
Termination: Maintain proper clearances from windows, doors, and air intakes.
Support: Secure pipes every 4 feet with appropriate hangers.
Sealing: Use primer and cement on all joints for airtight seal.
Combustion air: Install separate intake pipe of equal size to vent.

CAUTION! Improper venting can cause carbon monoxide poisoning and system failure.

Startup & Commissioning

Initial startup procedure and system verification.

Restore power: Turn on electrical disconnect and circuit breaker.
Open gas: Turn gas valve to ON position at meter and furnace.
Set thermostat: Raise temperature setting above room temperature.
Observe ignition: Watch for proper burner ignition sequence.
Check operation: Verify blower starts after appropriate delay.
Measure performance: Check temperature rise and gas pressure.
Test safety controls: Verify limit switches and pressure switches function.

WARNING! If furnace fails to ignite after three attempts, wait 5 minutes and diagnose before retrying.

Maintenance Guidelines

Routine maintenance for optimal performance and longevity.

Monthly: Check air filter; replace if dirty
Annual: Professional inspection and cleaning
Seasonal: Verify vent termination clear of obstructions
Biannual: Check drain line for clogs
As needed: Clean flame sensor and burners

CAUTION! Always disconnect power before performing any maintenance.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Furnace won't start	Power, thermostat, door switch	Check circuit breaker; verify thermostat setting; ensure door closed securely.
No heat	Gas supply, ignition, pressure switch	Verify gas valve open; check for spark at igniter; inspect pressure switch tubing.
Short cycling	Dirty filter, blocked vent, high limit	Replace air filter; check vent termination; verify proper airflow.
Blower runs continuously	Thermostat fan setting, control board	Check thermostat FAN setting; inspect control board for faults.
Unusual odors	Dust buildup, gas leak, electrical	Clean burners and heat exchanger; check for gas leaks; inspect electrical connections.

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

Service: 1-800-ARMSTRONG; www.armstrongair.com