Page 1
05/09
*2P0509*
505,065M
*P505065M*
E
2005 Lennox Industries Inc.
Dallas, Texas, USA
THIS MANUAL MUST BE LEFT WITH THE
HOMEOWNER FOR FUTURE REFERENCE
INSTALLATION
INSTRUCTIONS
G51MP SERIES UNITS
GAS UNITS
505,065M
05/2009
Supersedes 07/2007
Table of Contents
Unit Dimensions
2
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
G51MP Parts Identification
3
. . . . . . . . . . . . . . . . . . . . . .
Shipping and Packing List
4
. . . . . . . . . . . . . . . . . . . . . .
Safety Information
4
. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Use of Furnace as a Construction Heater
5
. . . . . . . . .
General
6
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Combustion, Dilution & Ventilation Air
6
. . . . . . . . . . . .
Installation − Setting Equipment
9
. . . . . . . . . . . . . . . . . .
Filters
16
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Duct System
16
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pipe & Fittings Specifications
16
. . . . . . . . . . . . . . . . . . . .
Vent Piping Guidelines
18
. . . . . . . . . . . . . . . . . . . . . . . . .
Joint Cementing Procedure
19
. . . . . . . . . . . . . . . . . . . . .
Venting Practices
19
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Gas Piping
31
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electrical
34
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Unit Start−Up
38
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Gas Pressure Adjustment
39
. . . . . . . . . . . . . . . . . . . . . .
High Altitude Information
41
. . . . . . . . . . . . . . . . . . . . . . .
Other Unit Adjustments
43
. . . . . . . . . . . . . . . . . . . . . . . . .
Service
46
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Planned Service
48
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Repair Parts List
48
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Troubleshooting
49
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Ignition Control Board Diagnostic Codes
52
. . . . . . . . . .
Vent Pipe Sizing Worksheet
53
. . . . . . . . . . . . . . . . . . . . .
Start−Up & Performance Check List
53
. . . . . . . . . . . . . .
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.
