Page 1
03/06
*2P0306*
505,181M
*P505181M*
©2006 Lennox Industries Inc.
Dallas, Texas, USA
RETAIN THESE INSTRUCTIONS
FOR FUTURE REFERENCE
INSTALLATION
INSTRUCTIONS
G40UH(X) Series
GAS FURNACE
505,181M
03/2006
Supersedes 505,011M
Table of Contents
Unit Dimensions 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
G40UH(X) Parts Arrangement 3. . . . . . . . . . . . . . . . . . . . .
G40UH(X) Gas Furnace 4. . . . . . . . . . . . . . . . . . . . . . . . . .
Shipping and Packing List 4. . . . . . . . . . . . . . . . . . . . . . . .
Safety Information 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
General 5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Combustion, Dilution & Ventilation Air 5. . . . . . . . . . . . . .
Setting Equipment 8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Filters 12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Duct System 12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Venting 12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Gas Piping 20. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electrical 21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Unit Start−Up 25. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Gas Pressure Adjustment 26. . . . . . . . . . . . . . . . . . . . . . .
High Altitude Information 27. . . . . . . . . . . . . . . . . . . . . . . .
Other Unit Adjustments 27. . . . . . . . . . . . . . . . . . . . . . . . . .
Service 28. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Repair Parts List 30. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Ignition Control Board Diagnostic Codes 31. . . . . . . . . . .
Troubleshooting 32. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Start−Up & Performance Check List 35. . . . . . . . . . . . . . .
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.
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