Lennox G51 User manual

G51
Single-stage, high-efficiency furnace
Home Comfort Systems
LENNOX’ ELITE®SERIES
G51 High-Efficiency Gas Furnace ◆92.1% AFUE

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Maximum comfort is yours with the Elite®Series G51 gas furnace. The G51
surrounds you in warmth, without undue noise. Its sound-absorbing,
insulated cabinet delivers smooth, quiet operation.
ENGINEERED FOR COMFORT AND EFFICIENCY
The G51 has a low-speed, continuous fan setting that provides maximum
comfort with remarkable efficiency, which means you’ll stay warm for less.
Elite®Series G51 Furnace
High efficiency can save you
hundreds of dollars each year
SureLight®Control delivers
starting reliability
Low-speed, continuous fan
setting provides a consistent
flow of air
ENERGY STAR®qualified
EFFICIENCY RATING
92.1% AFUE (Annual Fuel
Utilization Efficiency).
WARRANTY*
Limited lifetime warranty
on the heat exchanger.
5-year limited warranty
on all remaining covered
components.
Innovation never felt so good.
™
*Applies to residential applications only.
See actual warranty certificate for details.
EfficientCan give you
significant energy savings year
after year
The G51 gas furnace not only
keeps you warm—it also reduces
your energy costs. With an efficiency
rating of 92.1% AFUE (Annual
Fuel Utilization Efficiency), the
G51 offers more comfort for
your energy dollars.
ReliableDesigned and tested to ensure optimal performance
Every component of the G51 is rigorously tested in our dedicated research lab.
As a result, you can count on your new furnace to deliver the highest possible
level of reliability and performance.
This chart depicts potential energy savings you can
expect from the G51 gas furnace versus older furnaces
with lower efficiency ratings. Criteria used in this
example are 2,000 full-load heating hours, with a
60,000-Btuh heating design load and $1.281 ccf for
gas. Your actual savings will vary depending on the
weather, local fuel rates and your lifestyle.
Source: U.S. Department of Energy national average
energy rates.
AFUE
92.1 %
vs. 55%
92.1 %
vs. 65%
$4000
$3000
$2500
$2000
$1500
$1000
$500
0
$3378
3-YEAR HEATING SAVINGS
$2088
92.1% efficient G51 gas furnace vs.
55% and 65% equivalent AFUE units

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Elite®Series G51 Specifications
G51 24B-045 36B-045 36B-070 36C-090 48C-090 60C-090
AFUE 92.1% 92.1% 92.1% 92.1% 92.1% 92.1%
Dimensions HxWxD (in.) 40 x 17-1/2 x 28-1/2 40 x 17-1/2 x 28-1/2 40 x 17-1/2 x 28-1/2 40 x 17-1/2 x 28-1/2 40 x 21 x 28-1/2 40 x 21 x 28-1/2
HxWxD (mm) 1016 x 446 x 724 1016 x 446 x 724 1016 x 446 x 724 1016 x 446 x 724 1016 x 533 x 724 1016 x 533 x 724
G51 48C-110 60C-110 60D-135
AFUE 92.1% 92.1% 92.1%
Dimensions HxWxD (in.) 40 x 21 x 28-1/2 40 x 21 x 28-1/2 40 x 24-1/2 x 28-1/2
HxWxD (mm) 1016 x 533 x 724 1016 x 533 x 724 1016 x 622 x 724
Note: Due to Lennox’ ongoing commitment to quality, all specifications, ratings and dimensions are subject to change without notice.
Lennox is proud of
the fact that these
products have
earned the Good
Housekeeping Seal.
THIS MODEL
92.1%
INNOVATIVE FEATURES FOR ENHANCED COMFORT AND EFFICIENCY
G51
92.1% AFUE
Insulated Blower Compartment –
Reduces sound for quieter operation.
Duralok Plus®Heat Exchanger –
Made of high-quality, patented ArmorTuf™
aluminized steel. Life-tested to 2-1/2 times agency
requirements (ANSI standard Z21.47) for long
life and durability.
SureLight®Igniter –
Made of silicon nitride for reliable,
long-life performance
Robust Stainless Steel
Secondary Heat Exchanger –
Time-tested design allows the furnace to achieve
high efficiency levels by capturing additional heat.
SureLight Control Board –
Controls furnace operation to
ensure reliable, efficient performance.
Durable Steel Cabinet –
Built to last and coated with high-quality, textured-
paint finish.
Many Lennox®home
comfort systems meet
ENERGY STAR®requirements
when used with appropriate
components. Ask your
dealer for details.

PC55478(48M85) G51 09/08
© Lennox Industries Inc. 2007
Visit us at www.lennox.com, or contact us at 1-800-9-LENNOX.
1Air conditioner or heat pump
2Thermostat
3Furnace or air handler
4Filtration device
5Germicidal light
6Indoor coil
7Humidifier
8HEPA bypass filtration system
9Energy recovery ventilator
 Supply duct
 Return duct
 Dehumidifier system
 Residential generator
CUSTOMIZE YOUR COMFORT
Lennox®heating, cooling and indoor air quality products are designed to
provide efficient, economical comfort—not only as individual units, but also
together as an integrated system. This combined network of products delivers
on every comfort count, from consistent temperatures and balanced humidity to improved indoor air quality. Lennox
also offers a line of residential generators, which provide safe, reliable standby power in the event of outages.
DEALERS YOU CAN COUNT ON
Choosing the right dealer for your home’s heating, cooling and air quality needs is every bit as important as choosing the
right brand. We think you’ll agree our independent dealers are a big reason you can count on quality customer service
whenever you call. Your Lennox dealer’s dedication to quality shows in his knowledge, training and expertise in designing
the right system for your home, installing it properly and keeping it running perfectly for many years to come.