Lennox G50UH Series

Page 1
05/09
*2P0509*
505,254M
*P505254M*
E 2006 Lennox Industries Inc.
Dallas, Texas, USA
RETAIN THESE INSTRUCTIONS
FOR FUTURE REFERENCE
INSTALLATION
INSTRUCTIONS
G50UH(X) Series
GAS FURNACE
505,254M
05/2009
Supersedes 08/2006
Table of Contents
Unit Dimensions 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
G50UH(X) Parts Arrangement 3. . . . . . . . . . . . . . . . . . . .
G50UH(X) Gas Furnace 4. . . . . . . . . . . . . . . . . . . . . . . . . .
Shipping and Packing List 4. . . . . . . . . . . . . . . . . . . . . . . .
Safety Information 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Use of Furnace as a Construction Heater 5. . . . . . . . . . .
General 5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Combustion, Dilution & Ventilation Air 6. . . . . . . . . . . . . .
Setting Equipment 9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Filters 13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Duct System 13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Venting 13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Gas Piping 21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electrical 22. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Unit Start−Up 26. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Gas Pressure Adjustment 27. . . . . . . . . . . . . . . . . . . . . . . .
High Altitude Information 28. . . . . . . . . . . . . . . . . . . . . . . . .
Other Unit Adjustments 28. . . . . . . . . . . . . . . . . . . . . . . . . .
Blower Performance Data 29. . . . . . . . . . . . . . . . . . . . . . . .
Service 33. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Planned Service 34. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Repair Parts List 35. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Ignition Control Board Diagnostic Codes 35. . . . . . . . . . .
Troubleshooting 36. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Start−Up & Performance Check List 40. . . . . . . . . . . . . . . .
WHAT TO DO IF YOU SMELL GAS:
Do not store or use gasoline or other
flammable vapors and liquids in the
vicinity of this or any other ap-
pliance.
Installation and service must be
performed by a qualified installer,
service agency or the gas supplier.
D Do not try to light any appliance.
D Do not touch any electrical switch; do not
use any phone in your building.
D Immediately call your gas supplier from a
neighbor’s phone. Follow the gas supplier’s
instructions.
D If you cannot reach your gas supplier, call
the fire department.
FIRE OR EXPLOSION HAZARD.
Failure to follow safety warnings exact-
ly could result in serious injury, death,
or property damage.
WARNING
D Leave the building immediately.
Litho U.S.A.

Lennox G50UH Series Specifications

General

Vent Type	Natural Draft
Heat Exchanger Material	Aluminized Steel
Efficiency	80%
Stages	Single Stage
Fuel Type	Natural Gas/Propane
Warranty	Limited Lifetime Heat Exchanger Warranty, 5-Year Limited Warranty on Covered Components
Cabinet Type	Upflow/Horizontal

Summary

Safety Information

General Safety Precautions

Covers crucial warnings, dangers, and cautions for safe furnace operation and handling.

Gas Leak Detection and Response

Provides essential steps for detecting and responding to gas leaks to prevent fire or explosion.

Installation Guidelines

Combustion and Ventilation Air

Air Supply Requirements

Explains the critical need for sufficient combustion air and ventilation for efficient and safe furnace operation.

Contaminants in Combustion Air

Confined Space Air Requirements

Confined Space Ventilation

Specifies air intake and ventilation requirements for furnaces installed in confined spaces.

Setting Equipment and Clearances

Furnace Placement and Clearances

Return Air Configuration

Horizontal Installation Specifics

Horizontal Installation Safety

Highlights critical safety warnings related to combustion products and duct connections in horizontal installations.

Masonry Chimney Venting

Venting with Masonry Chimneys

Advanced Venting and Chimney Requirements

General Venting Requirements

Gas Piping

Gas Supply Connection

Gas Piping Safety Precautions

Highlights critical safety precautions and prohibitions related to gas piping installation and materials.

Electrical and Leak Testing

Electrical Wiring and ESD Precautions

Covers safe electrical wiring practices and precautions to prevent damage from electrostatic discharge.

Gas Piping Leak Detection

Explains methods for performing leak checks on gas piping connections, including crucial safety warnings.

Wiring Diagrams

Typical Field Wiring Diagram

Integrated Control Board Layout

Schematic Wiring Diagram

Furnace Schematic Wiring Diagram

Offers a comprehensive schematic wiring diagram illustrating the furnace's internal electrical pathways and components.

Unit Start-Up and Gas Valve Operation

Furnace Start-Up Procedure

Guides the user through the essential steps for safely starting up the furnace for the first time.

Gas Pressure and Flow Rate

Gas Pressure Adjustment

Details procedures for checking and adjusting manifold pressure for natural gas and LP/propane.

Blower Performance Data and Troubleshooting

Troubleshooting Unit Failures

Lists common causes for furnace failure to operate and checks to perform for diagnosis.

Planned Service and Safety

Annual Inspection Checklist

Gas Leak Detection Safety

Provides a critical caution regarding the use of leak detection solutions and avoiding ignition sources.

Parts and Diagnostics

Ignition Control Diagnostic Codes

Explains diagnostic codes indicated by LED flashes for troubleshooting ignition and control board issues.

Heating Sequence Troubleshooting

Normal Heating Sequence Flowchart

Cooling Sequence Troubleshooting

Normal Cooling Sequence Flowchart

Start-Up and Performance Checklist

Performance Check List Form

A comprehensive checklist for recording start-up parameters and performance checks for the installed furnace.