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1998 Lennox Industries Inc.
Litho U.S.A.
Corp. 9723-L12
G24M
Service Literature
Revised 07-2001
G24M SERIES UNITS
G24M series units are mid-efficiency gas furnaces manufac-
tured with tubular steel heat exchangers formed of alumi-
nized steel. G24M units are available in heating capacities of
45,000 to 140,000 Btuh and cooling applications up to 5
tons. Refer to Engineering Handbook for proper sizing.
Units are factory equipped for use with natural gas. A kit is
available for conversion to LPG operation. Early model G24M
units use electronic (direct spark) ignition. Late model G24M
model units feature the Lennox SureLight
T
silicon-nitride
ignition system. The G24MX unit meets the California Nitro-
gen Oxides (NO
x
) Standards and California Seasonal Effi-
ciency requirements. All units use a redundant gas valve to
assure safety shut-off as required by A.G.A. or C.G.A.
Units may be installed in upflow, downflow or horizontal posi-
tion. The heat exchanger is designed for upright or horizon-
tal use only. When the unit is installed in the downflow posi-
tion, the heat exchanger is field removed and reinstalled so it
is upright when the cabinet is inverted. No field conversion is
required when the unit is installed in the horizontal position.
The heat exchanger, burners and manifold assembly can
easily be removed for inspection and service by simply dis-
connecting gas, unplugging wiring harness and spark wires
and removing four screws holding the heat exchanger in
place. Then the heat exchanger slides out of the cabinet.
All specifications in this manual are subject to change. Pro-
cedures outlined in this manual are presented as a recom-
mendation only and do not supersede or replace local or
state codes. In the absence of local or state codes, the
guidelines and procedures outlined in this manual (except
where noted) are recommended only and do not constitute
code.
SPECIFICATIONS
Model No.
G24M2(X)-45
G24M2-60
G24M3(X)-60
G24M2-75
G24M3(X)-75
Input Btuh (kW)
45,000 (13.2)
60,000 (17.6)
75,000 (22.0)
Output Btuh (kW)
36,900 (10.8)
49,200 (14.4)
61,700 (18.1)
l
A.F.U.E.
80.1%
80.5%
80.5%
80.1%
80.0%
California Seasonal Efficiency
75.4%
76.4%
75.9%
76.8%
76.8%
Flue size connection diameter — in. (mm) round
3 (76)
4 (102)
Temperature rise range —
_
F (
_
C)
30 - 60 (17 - 33)
45 - 75 (25 - 42)
High static certified by A.G.A./C.G.A. — in wg. (Pa)
.50 (125)
Gas Piping Size I.P.S. Natural or LPG/propane
1/2 (13)
Blower wheel nominal
in.
9 x 7
10 x 7
9 x 7
10 x 7
Blower wheel nominal
diameter x width
mm
229 x 178
254 x 178
229 x 178
254 x 178
Blower motor output — hp (W)
1/4 (187)
1/3 (224)
1/4 (187)
1/3 (224)
Nominal cooling
Tons
1, 1-1/2 or 2
2, 2-1/2 or 3
1, 1-1/2 or 2
2, 2-1/2 or 3
Nominal cooling
that can be added
kW
3.5, 5.3 or 7.0
7.0, 8.8 or 10.6
3.5, 5.3 or7.0
7.0, 8.8 or 10.6
Shipping weight — lbs. (kg) 1 package
130 (59)
135 (61)
Electrical characteristics
120 volts — 60 hertz — 1 phase (less than 12 amps) All models
b
Optional Accessories (Must Be Ordered Extra)
b
LPG/propane kit
LB-69845L
(38K84)
Twinning Kit
96J69
— 5 lbs. (2 kg)
Up-Flow/Horizontal Filter and Filter Rack Kits
}
No. & size of filters - in. (mm)
Single (
32J02
) Ten Pack (
66K64
)
(1) 16 x 20 x 1 (406 x 508 x 25)
¡
Down-flow
Catalog No.
LB-69843A
(32J01)
— 3 lbs. (1 kg)
¡
Down-flow
Filter Kit
No. & Size of Filters — in. (mm)
(2) 16 x 20 x 1 (406 x 508 x 25)
Down-flow Combustible Floor Base
LB-79239A
(67J91)
— 10 lbs. (4 kg)
Sidewall Power Venting Kit
79J15
— 25 lbs. (11 kg)
Hanging Bracket Kit
LB-69957
(46J66)
— 15 lbs. (8 kg)
l
Annual Fuel Utilization Efficiency based on U.S. DOE test procedures and according to FTC labeling regulations. Isolated combustion system rating for non-weatherized
furnaces.
}
Polyurethane frame type filter is furnished with kit.
¡
Filters are not furnished with kit and must be ordered extra.