Lennox Enlight LGT Series Manual

S e r v i c e L i t e r a t u r e
The LGT156, 180, 210, 240 and 300 units are configure to
order units (CTO) with a wide selection of factory installed
options.
The LGT156 \ 300 is available in 169,000 to 480.000 Btuh.
See SPECIFICATIONS-GAS HEAT for more detail per
model.
Gas heat sections are designed with aluminized steel tube
heat exchangers with stainless steel as an option.
Cooling capacities range from 13 to 25 tons. LGT 156 uti-
lize two compressors and three condenser fans. LGT 180
utilize three compressors and four condenser fans. LGT
210 utilize four compressors and four condenser fans.
LGT 240 & 300 utilize four compressors and six condens-
er fans.
Multi-Stage Air Volume MSAV® blower option is available.
The VFD-driven blower will operate at lower speeds when
demand is low and increase to higher speeds when de-
mand is high.
Variable speed VAV system is available as an option which
enables supply duct static measurement to control blow-
er CFM and discharge air temperature to control cooling
stages.
All LGT units are designed to accept any of several differ-
ent energy management thermostat control systems with
minimum field wiring. Factory- or field-provided control op-
tions connect to the unit through Smartwire connectors.
When "plugged in" the controls become an integral part of
the unit wiring.
The CORE Control System is designed to accelerate
equipment install and service. Standard with all Enlight
rooftop units, control system integrates key technologies
that lower installation costs, drive system efficiency, and
protect your investments.
The CORE Unit Controller is a microprocessor-based
controller that provides flexible control of all unit functions.
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.
UNIT INFORMATION UNIT INFORMATION
100081
Revised 08/2021
LGT156 through 300
Page 1
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
maintenance), disable power to blower, remove
fan belt where applicable, and ensure all
controllers and thermostats are set to the "OFF"
position before performing maintenance.
3- Always keep hands, hair, clothing, jewelry, tools,
etc., away from moving parts.
WARNING
Improper installation,
service or maintenance can cause property damage,
personal injury or loss of life. Installation and service
must be performed by a licensed professional HVAC
installer or equivalent, service agency, or the gas
supplier

Table of Contents

Options / Accessories . . . . . . . . . . . . . . . . . . . . . Page 2
Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 6
Gas Heat Specifications / High Altitude . . . . . . Page 11
Blower Data.. . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 12
Electrical Data. . . . . . . . . . . . . . . . . . . . . . . . . . . Page 15
Unit Parts Arrangement . . . . . . . . . . . . . . . . . . . Page 18
I-Unit Components . . . . . . . . . . . . . . . . . . . . . . . Page 18
II-Placement and Installation . . . . . . . . . . . . . . . Page 37
III-Charging. . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 37
IV Start Up - Operation . . . . . . . . . . . . . . . . . . . . Page 63
V-System Service Checks . . . . . . . . . . . . . . . . . Page 65
VI-Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . Page 67
VII-Accessories. . . . . . . . . . . . . . . . . . . . . . . . . . Page 68
VIII-Hot Gas Re-Heat . . . . . . . . . . . . . . . . . . . . . Page 73
IX-Staged Blower . . . . . . . . . . . . . . . . . . . . . . . . Page 78
X - VAV System . . . . . . . . . . . . . . . . . . . . . . . . . . Page 50
XI-Wiring and Operation Sequence
LGT SERIES
13 to 25 ton
45.7 to 88 kW
adjustment, alteration,
. . . . . . . . . Page 82