Lennox LGM240 User Manual

Page 1
UNIT INFORMATIONUNIT INFORMATION
Service Literature
WARNING
Improper installation, adjustment, alteration, 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.
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 disconnect switch(es).
Unit may have multiple power supplies.
Table of Contents
Options / Accessories . . . . . . . . . . . . . . . . . . .Page 2


Blower Data . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 10
Electrical Data . . . . . . . . . . . . . . . . . . . . . . . . . Page 13


II-Placement and Installation . . . . . . . . . . . . . . .Page 33
III-Charging . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 33
IV-Start Up - Operation . . . . . . . . . . . . . . . . . . . Page 35
V-System Service Checks . . . . . . . . . . . . . . . . .Page 37

VII-Accessories . . . . . . . . . . . . . . . . . . . . . . . . .Page 40
VIII-Hot Gas Re-Heat . . . . . . . . . . . . . . . . . . . . Page 44
IX-Staged Blower . . . . . . . . . . . . . . . . . . . . . . . Page 48
X - VAV System . . . . . . . . . . . . . . . . . . . . . . . . .Page 50
XI-Wiring and Operation Sequence . . . . . . . .Page 52
-
ure to order units (CTO) with a wide selection of factory
installed options.
         
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 (45.7 to 88
kW).
-
denser fans, while LGM210, 240 and 300 utilize four com-
pressors and six condenser 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.
󰀨-
ent energy management thermostat control systems with
-
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 Model L™
rooftop units, control system integrates key technologies
 󰀩 
protect your investments.
The CORE Unit Controller is a microprocessor-based con-

Information contained in this manual is intended for use

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.
LGM SERIES
13 to 25 ton
45.7 to 88 kW
100024
Revised 08/2021
LGM156U through 300U

Lennox LGM240 Specifications

General

Fuel Type	Natural Gas
AFUE	80%
Stages	Single Stage
Ignition Type	Hot Surface Ignition
Blower Motor	PSC (Permanent Split Capacitor)
Warranty	5-Year Limited Warranty on Covered Components

Summary

UNIT INFORMATION

Safety Warnings

Highlights critical safety precautions for installation, service, and maintenance.

OPTIONS AND ACCESSORIES

Economizer Options

Describes available economizer system options and controls.

SPECIFICATIONS

General Data & Cooling Performance

Provides key specifications for tonnage, efficiency, and cooling performance.

Blower & Drive Specs

Lists specifications for indoor blowers, motors, and drive kits.

SPECIFICATIONS - GAS HEAT

Heat Input Performance

Provides gas heat input and output performance data for two-stage and four-stage units.

BLOWER DATA

Blower Performance Tables

Presents performance data for blower operation at various static pressures.

Factory Installed Drive Kits

Details specifications for factory-installed belt drive kits and RPM ranges.

UNIT COMPONENTS

Refrigerant Circuit Diagrams

Illustrates refrigerant flow for reheat and cooling modes.

B-Cooling Components

Compressors & Crankcase Heaters

Details compressor types, capacity variation, and crankcase heaters.

High & Low Pressure Switches

Explains the function and operation of pressure switches.

II-PLACEMENT AND INSTALLATION

Installation Checks

Provides essential checks before unit startup for proper installation.

D-Blower Belt Adjustment

Belt Tension Check

Details how to check belt tension using deflection force.

D-GAS HEAT COMPONENTS

Control & Ignition Modules

Describes control box components and burner ignition controls.

Burner Ignition Control Details

Explains the functions and LED codes of the UTEC ignition control.

3-Burner Assembly

High Temperature Limits

Explains the function of primary high temperature limits S10 and S99.

Gas Valves & Regulation

Describes gas valve operation, adjustment, and pressure regulation.

III-CHARGING

Refrigerant Charge Procedure

Provides a procedure for checking and charging refrigerant.

IV-STARTUP - OPERATION

Preliminary Checks

Lists essential checks before starting the unit.

Cooling Startup Sequence

Details the sequence of operations for cooling startup.

C-Heating Startup

Safety Precautions & Furnace Operation

Outlines safety warnings and the procedure for furnace operation.

V-SYSTEMS SERVICE CHECKS

Gas Piping Checks

Manifold Pressure Adjustment

VIII-FACTORY-INSTALLED Hot Gas Re-Heat

Reheat Operation & Setpoint

Reheat Operation Table

IX--Multi-Staged Blower

Design Specifications & Speeds

Minimum Position Settings

X-VAV System

Start-Up & Setpoints

Manual VFD Bypass

XI-Wiring Diagrams and Sequence of Operation

Gas Heat Diagram & Key List

Provides the gas heat wiring diagram and a component key list.

Gas Heat Sequence of Operation

Details the sequence of operation for gas heat stages.

Thermostat Wiring Diagram

Shows the wiring connections for the thermostat.

Economizer Wiring Diagram

Illustrates the wiring connections for the economizer system.

Cooling Sequence of Operation

Details the sequence of operation for cooling stages.