Lennox G51MP User Manual



E 2003 Lennox Industries Inc.

Dallas, Texas, USA

504,666M
08/03

G51MP

SERIES

GAS FURNACE

FIRE OR EXPLOSION HAZARD.

Failure to follow safety warnings exactĆ
ly could result in serious injury, death,
or property damage.

Do not store or use gasoline or other
flammable vapors and liquids in the
vicinity of this or any other apĆ
pliance.

Installation and service must be
performed by a qualified installer,
service agency or the gas supplier.

08/03

*2P0803*

Litho U.S.A.

WARNING

WHAT TO DO IF YOU SMELL GAS:

D Do not try to light any appliance.
D Do not touch any electrical switch; do not

use any phone in your building.

D Leave the building immediately.
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.

504,666M

*P504666M*

G51MP Parts Identification

TOP CAP

UPPER ACCESS

PANEL

COMBUSTION AIR

INDUCER

DURALOK

EXCHANGER

ASSEMBLY

TM

HEAT

BURNERS

CABINET

GAS VALVE AND

MANIFOLD

FLUE

COLLAR

COMBUSTION AIR

PROVING

(PRESSURE)

SWITCH

SURELIGHTt

CONTROL BOARD

BLOWER ACCESS

PANEL

FIGURE 1

WARNING

Product contains fiberglass wool.

Disturbing the insulation in this product during
installation, maintenance, or repair will expose you
to fiberglass wool. Breathing this may cause lung
cancer. (Fiberglass wool is known to the State of CalĆ
ifornia to cause cancer.)

Fiberglass wool may also cause respiratory, skin,
and eye irritation.

To reduce exposure to this substance or for further
information, consult material safety data sheets
available from address shown below, or contact your
supervisor.

Lennox Industries Inc.
P.O. Box 799900
Dallas, TX 75379-9900

NOTE - This manual must be left with the equipment
user.

BLOWER

MOTOR

CONTROL BOX

WARNING

Do not set thermostat below 60°F (16°C) in heating
mode. Setting thermostat below 60°F (16°C) reduces
the number of heating cycles. Damage to the unit
may occur that is not covered by the warranty.

WARNING

If overheating occurs or if gas supply fails to shut off,
shut off the manual gas valve to the furnace before
shutting off electrical supply.

CAUTION

Before attempting to perform any service or mainteĆ
nance, turn the electrical power to unit OFF at the
disconnect switch.

Page 2

WARNING

Do not use this furnace if any part has been underĆ
water. A flood-damaged furnace is extremely danĆ
gerous. Attempts to use the furnace can result in
fire or explosion. Immediately call a qualified serĆ
vice technician to inspect the furnace and to replace
all gas controls, control system parts, and electrical
parts that have been wet or to replace the furnace,
if deemed necessary.

IMPORTANT

Any additions, changes, or conversions required in
order for the appliance to satisfactorily meet the apĆ
plication needs must be made by a Lennox service
technician using factory specified and approved
parts.

WARNING

Improper installation, adjustment, alteration, service
or maintenance can cause property damage, personĆ
al injury or loss of life. Installation and service must
be performed by a qualified installer, service agency
or the gas supplier.

Safety Instructions

1 - Keep the furnace area clear and free of combustible

material, gasoline, and other flammable vapors and
liquids. If it is installed in an insulated area, the furnace
must be kept free of insulating material. Insulating maĆ
terial may be combustible.

2 - DO NOT obstruct air flow to unit. Unit must receive an

unobstructed flow of combustion and ventilating air.
DO NOT block or obstruct air openings on the furnace
or air openings to the area in which the furnace is
installed. Take care to maintain established clearĆ
ances surrounding the furnace.

3 - DO NOT store chlorine or fluorine products near unit

or introduce these products into the combustion air.
These products can cause furnace corrosion.

4 - DO NOT draw return air from a room where this furĆ

nace, or any other gas appliance (ie., a water heatĆ
er), is installed. When return air is drawn from a room,

a negative pressure is created in the room. If a gas apĆ
pliance is operating in a room with negative pressure,
the flue products can be pulled back down the vent
pipe and into the room. This reverse flow of the flue
gas may result in incomplete combustion and the
formation of carbon monoxide gas. This toxic gas
might then be distributed throughout the house by the
furnace duct system.

WARNING

The blower door must be securely in place when the
blower and burners are operating. Gas fumes, which
could contain carbon monoxide, can be drawn into
the living space resulting in personal injury or death.

Your furnace is a gas appliance. It is critical that the gas

supplied to the unit be completely burned to avoid the proĆ
duction of carbon monoxide gas. Complete combustion of
the gas requires, but is not limited to, correct gas pressure
and gas flow rate, adequate combustion, air, and proper
venting.

WARNING

Carbon monoxide gas is invisible, odorless and
toxic.

Exposure to carbon monoxide gas can cause personal injuĆ
ry and even death to all occupants, including pets. Any item
that is powered by or gives off heat from a combustion proĆ
cess (including lawn mowers, automobiles, and fireplaces)
has the potential to produce carbon monoxide gas. Because
of this, Lennox recommends the use of a carbon monoxĆ

ide detector in your home, even if you do not own gas
appliances. Reliable detectors are available at reasonable

retail prices. Contact your Lennox dealer for more details
about this investment in your safety.

Your furnace is designed to meet standards set by nationĆ
al agencies, and to operate safely when properly installed
and maintained. However, the unit's performance can be
greatly impacted by the individual installation and the opĆ
erating environment. It is your responsibility to ensure that
this appliance is maintained. Proper maintenance is critiĆ
cal for your safety and the satisfactory operation of the
product. Lennox strongly recommends annual inĆ
spection and maintenance of this appliance. Contact
your Lennox dealer for an inspection by a qualified service
technician.

Lighting Information & Operation

WARNING

If you do not follow these instructions exactly, a fire
or explosion may result causing property damage,
personal injury or death.

BEFORE LIGHTING the unit, smell all around the apĆ

pliance area for gas. Be sure to smell next to the floor beĆ
cause some gas is heavier than air and will settle on the
floor.

Page 3