installation manual furnace gua120a020

The GUA120A020 furnace is a high-efficiency residential heating system with 120,000 BTU capacity, featuring electronic ignition, variable-speed blower motor, multi-speed operation, and compatibility with various thermostat systems. Designed for forced-air applications with AFUE ratings up to 96%, this natural gas furnace includes safety controls, diagnostic LED indicators, and requires professional installation. Below are essential sections covering safety precautions, installation procedures, setup guidelines, specifications, and troubleshooting.

1. Safety Precautions 2. Pre-Installation Requirements 3. Installation Procedures 4. Electrical Connections 5. Gas Line Connections 6. Venting System Installation 7. Startup and Commissioning 8. Specifications 9. Control Settings 10. Maintenance Guidelines 11. Troubleshooting

Safety Precautions

Critical safety measures must be followed during installation and operation.

Hazard	Precaution
Gas Leaks	Check all connections with leak detection solution; never use open flame
Electrical Shock	Disconnect power before servicing; ensure proper grounding
Carbon Monoxide	Install CO detectors; ensure proper venting
Fire Hazard	Maintain clearance from combustibles; install smoke detectors
Burn Risk	Allow unit to cool before servicing; wear protective equipment

Pre-Installation Requirements

Site preparation and verification before installation.

Location: Indoor installation only; minimum clearances: 1" sides, 6" front, 24" top.
Foundation: Level, solid concrete or approved masonry base.
Combustion Air: Verify adequate fresh air supply per local codes.
Gas Supply: Confirm natural gas availability; pressure 6-7 inches WC.
Electrical: 120V, 60Hz dedicated circuit; proper grounding required.

WARNING! Installation must comply with all local codes and regulations. Professional installation required.

Installation Procedures

Step-by-step furnace installation process.

Position furnace: Place on level foundation in approved location.
Ductwork connection: Install supply and return ducts; seal all joints.
Remove shipping materials: Remove all protective covers and shipping restraints.
Filter installation: Install approved air filter in filter rack.
Condensate drain: Connect PVC drain line to condensate trap.

CAUTION! Furnace is heavy; use proper lifting equipment and techniques.

Electrical Connections

Power Supply: 120V AC, 60Hz, 15 amp circuit
Thermostat: Low voltage connections (R, W, G, Y terminals)
Grounding: Proper equipment grounding mandatory
Blower Motor: Variable speed ECM motor with speed taps
Control Board: Integrated furnace controller with diagnostic LEDs

WARNING! Disconnect power before making electrical connections.

Gas Line Connections

Natural gas piping and connection requirements.

Gas pipe sizing: Minimum 3/4" black iron pipe for entire run
Shutoff valve: Install approved gas shutoff valve within 6 feet
Drip leg: Install sediment trap before gas valve connection
Pressure test: Test at 14" WC for 10 minutes; no pressure drop
Leak check: Use leak detection solution on all connections

DANGER! Gas leaks can cause explosion or fire. Test thoroughly.

Venting System Installation

Category IV venting requirements for high-efficiency furnace.

Component	Requirement
Vent Material	PVC or CPVC Schedule 40
Vent Size	2" or 3" diameter per installation manual
Vent Slope	1/4" per foot toward furnace
Clearances	1" from combustible materials
Termination	12" minimum above grade/snow line

Startup and Commissioning

Initial startup procedure and system verification.

Power on: Restore electrical power to furnace
Gas supply: Open main gas valve and appliance shutoff valve
Thermostat: Set to heating mode; raise temperature above room temp
Sequence verification: Observe ignition sequence and flame establishment
Temperature rise: Measure temperature rise; adjust blower speed if needed
Combustion analysis: Verify CO levels and combustion efficiency

Specifications

Model: GUA120A020
Input Capacity: 120,000 BTU/H
Output Capacity: 115,000 BTU/H
AFUE: Up to 96%
Gas Type: Natural Gas
Electrical: 120V/60Hz/1Ph
Blower Motor: ECM Variable Speed
Dimensions: 21"W x 56"H x 26"D
Shipping Weight: 185 lbs
Vent Size: 2" PVC

Control Settings

Furnace control board settings and adjustments.

DIP Switch Settings: Blower speeds (COOL, HEAT), Fan ON delay, Fan OFF delay

Diagnostic LEDs: Flash codes for normal operation and fault conditions

Gas Valve: Factory set pressure; do not adjust unless qualified

Limit Switches: Auto-reset rollout and high limit protection

Maintenance Guidelines

Routine maintenance requirements for optimal performance.

Monthly: Check air filter; replace when dirty
Annual: Professional inspection and cleaning
Blower assembly: Clean annually; check motor amperage
Heat exchanger: Visual inspection for cracks or damage
Vent system: Inspect for obstructions or damage
Drain system: Clean condensate trap and drain lines

Troubleshooting

Symptom	Possible Cause	Corrective Action
No heat	Power, thermostat, gas supply	Check circuit breaker, thermostat setting, gas valve position
Furnace won't start	Door switch, limit control	Ensure door properly closed; reset rollout switch if tripped
Short cycling	Dirty filter, airflow restriction	Replace filter; check for blocked vents or registers
Blower runs continuously	Thermostat fan setting	Check thermostat fan setting (AUTO/ON); faulty fan relay
Ignition failure	Gas supply, igniter, pressure switch	Verify gas pressure; check igniter for cracks; clear vent obstruction

Service: Contact qualified HVAC technician for complex issues

Warranty: Limited lifetime heat exchanger; 10 years parts