FIGURE 1
G26 FURNACE
G26 HEAT EXCHANGE ASSEMBLY
Combustion Process:
1. A call for heat starts the combustion air blower.
2. Outdoor air is drawn through pipe into the burner
compartment where it mixes with gas in a con-
ventional style inshot burner.
3. The SureLight ignition system lights the burners.
4. Combustion products are drawn downward
through the heat exchanger. Heat is extracted
as indoor air passes across the outside surface
of the metal.
5. Latent heat is removed from the combustion
products as air passes through the coil. Conden-
sate (water) is formed as the combustion prod-
ucts cool.
6. As the combustion products exit the coil, con-
densate is collected and drained away.
7. Combustion products are pulled from the heat
exchanger and forced into the flue.
7
5
4
6
2
3
1
Page 1
© 1997 Lennox Industries Inc.
Litho U.S.A.
Corp. 9721−L11
G26
Service Literature
Revised 08−2004
G26 SERIES UNITS
G26 series units are high−efficiency upflow gas furnaces manufactured with
DuralokPlus aluminized steel clamshell-type heat exchangers. G26 units
are available in heating capacities of 50,000 to 125,000 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 con-
version to LPG operation. G26−1 and −2 model units use electronic (intermit-
tent pilot) ignition. G26−3, −4, −5 and −6 model units feature the Lennox Sur-
eLight silicon nitride ignition system. Each unit meets the California Nitro-
gen Oxides (NO
x
) Standards and California Seasonal Efficiency require-
ments without modification. All units use a redundant gas valve to assure
safety shut−off as required by A.G.A. or C.G.A.
Information contained in this manual is intended for use by qualified service
technicians only. All specifications are subject to change. Procedures out-
lined in this manual are presented as a recommendation only and do not su-
persede 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.
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