100074
LGT SERIES
Service Literature
7.5 to 12.5 ton
LGT092H through 150H
WARNING
To prevent serious injury or death:
1- Lock-out/tag-out before performing maintenance.
2- If system power is required (e.g., smoke detector main
tenance), disable power to blower, remove fan belt
where applicable, and ensure all controllers and ther
mostats are set to the “OFF” position before
performing maintenance.
3- Always keep hands, hair, clothing, jewelry, tools, etc.,
away from moving part
s.
The LGT092H-150H units are configure to order units
(CTO) with a wide selection of factory-installed options.
Units are available in 130,000, 180,000 Btuh or 240,000
Btuh (38.1, 52.7 or 70.3 kW) heating inputs. Gas heat sec
tions are designed with aluminized steel tube heat ex
changers with stainless steel as an option.
Cooling capacities range from 7.5 to 12.5 tons. All units are
equipped with two compressors.
All models are equipped with direct drive blowers. The
blower will operate at lower speeds when demand is low
and increase to higher speeds when demand is high.
The following examples show the model numbers of ten-
ton units with all available blower options:
LGT120H4E Single Zone MSAV Direct Drive
LGT120H4P VAV Direct Drive
All models are equipped with all aluminum condenser coils
with one two stage scroll compressor and one single stage
compressor.. Units can operate from 0°F to 125°F..
Units are also designed for R410A refrigerant. See unit
nameplate. Operating pressures and pressure switch set
tings are significantly higher than R22 charged units. Ser
vice equipment must be rated for R410A.
All LGT units are designed to accept any of several different
energy management thermostat control systems with mini
mum field wiring. Factory or field provided control options
connect to the unit with jack plugs. When ”plugged in” the
controls become an integral part of the unit wiring.
Information contained in this manual is intended for use by
qualified service technicians only. All specifications are
subject to change. Procedures outlined in this manual are
presented as a recommendation only and do not super
sede or replace local or state codes.
If the unit must be lifted for service, rig unit by attaching four
cables to the holes located in the unit base rail (two holes at
each corner). Refer to the installation instructions for the
proper rigging technique.
Table of Contents
Options / Accessories Page 2.....................
Specifications Page 5............................
Blower Tables Page 8...........................
Electrical Data Page 11...........................
Parts Arrangement Page 13.......................
I-Unit Components Page 14.......................
II-Placement and Installation Page 30...............
III-Charging Page 30..............................
IV-Start Up - Operation Page 35....................
V-System Service Checks Page 37................
VI-Maintenance Page 39..........................
VII-Accessories Page 40..........................
VIII-Direct Drive Supply Air Blower Page 50..........
IX-Staged Supply Air Operation Page 51............
XI-Wiring and Operation Sequence Page 52.........
WARNING
Improper installation, adjustment, alteration, service
or maintenance can cause property va, personal in
jury or loss of life. Installation and service must be
performed by a licensed professional HVAC installer
or equivalent, service agency, or the gas supplier
CAUTION
As with any mechanical equipment, contact with
sharp sheet metal edges can result in personal in
jury. Take care while handling this equipment and
wear gloves and protective clothing.
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