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© 2004 Lennox Industries Inc.
Litho U.S.A.
Corp. 0416−L4
G43UF
Service Literature
Revised 2−2006
G43UF SERIES UNITS
G43UF series units are high−efficiency gas furnaces
manufactured with Lennox DuralokPlust aluminized
steel clamshell−type heat exchangers, with a stainless steel
condensing coil. G43UF units are available in heating in-
put capacities of 44,000 to 132,000 Btuh (13 to 38.6 kW) and
cooling applications from 2 through 5 tons (7.0 through 17.6
kW). 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. All G43UF
units are equipped with a hot surface ignition system. The
gas valve is redundant to assure safety shut−off as re-
quired by C.S.A.
The heat exchanger, burners and manifold assembly can be
removed for inspection and service. The maintenance section
gives a detailed description on how this is done.
Information contained in this manual is intended for use by
qualified service technicians only. All specifications are sub-
ject to change. Procedures outlined in this manual are pre-
sented as a recommendation only and do not supersede or
replace local or state codes.
WARNING
Electric shock hazard. Can cause injury
or death. Before attempting to perform
any service or maintenance, turn the
electrical power to unit OFF at discon-
nect switch(es). Unit may have multiple
power supplies.
Table of Contents
General 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Specifications 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Blower Performance Data 4. . . . . . . . . . . . . . . . . . . . . .
I−Unit Components 9. . . . . . . . . . . . . . . . . . . . . . . . . . . .
II Placement and Installation 18. . . . . . . . . . . . . . . . . . . .
III−Start−Up 31. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
IV−Heating System Service Checks 32. . . . . . . . . . . . . .
V−Typical Operating Conditions 35. . . . . . . . . . . . . . . . .
High Altitude 35. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
VI−Maintenance 37. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
VII−Wiring and Sequence of Operation 39. . . . . . . . . . .
VIII−Troubleshooting 49. . . . . . . . . . . . . . . . . . . . . . . . . . .
IMPORTANT
Improper installation, adjustment, alteration, service
or maintenance can cause property damage, person-
al injury or loss of life. Installation and service must
be performed by a qualified installer, service agency
or the gas supplier.
WARNING
Sharp edges.
Be careful when servicing unit to avoid sharp edges
which may result in personal injury.
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