Lennox LGT048 - User Manual

2022
WARNING
Improper installation, adjustment, alteration, ser
vice or maintenance can cause property damage,
personal injury or loss of life. Installation and ser
vice must be performed by a licensed professional
HVAC installer or equivalent, service agency, or the
gas supplier
Table Of Contents
Dimensions Page 2.................................
Parts Arrangements Page 3.........................
Shipping and Packing List Page 4....................
General Page 4....................................
Requirements Page 4...............................
Unit Support Page 5................................
Duct Connection Page 6............................
Rigging Unit For Lifting Page 6.......................
Horizontal Air Discharge Page 6......................
Condensate Drains Page 7..........................
Gas Piping Page 8.................................
Pressure Test Gas Piping Page 9.....................
High Altitude Derate Page 10.........................
Download Mobile Service App Page 10.................
Electrical Connections Page 10.......................
Blower Operation and Adjustments Page 13............
Cooling Start-Up Page 21............................
Prognostic & Diagnostic Sensors Page 30..............
Cooling Operation Page 33...........................
INSTALLATION
INSTRUCTIONS
LGT/LCT036, 048,
060, 072
3, 4, 5 and 6 Ton
GAS AND COOLING PACKAGED UNITS
508286-01
7/2022
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 mainte
nance), 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 part
s.
Gas Heat Start-Up Page 34...........................
Heating Operation and Adjustments Page 35............
Electric Heat Start-Up Page 35........................
Hot Gas Reheat Startup Page 36......................
Service Page 38....................................
Factory Unit Controller Settings Page 49...............
RETAIN THESE INSTRUCTIONS FOR FUTURE REFERENCE
Use this QR code to download the mobile service app. Follow the prompts
to pair the app with the unit control system and configure the unit. Refer to the
“Download Mobile App” section in this manual and the Setup Guide provided
with this unit. The QR code is also available in the unit control area.
The app can be downloaded from the appropriate iOS or Android store.
Look for the following icon.
Attention!

Lennox LGT048 Specifications

General

Refrigerant Type	R-410A
Compressor Type	Scroll
Voltage	208/230V
Phase	1
Cooling Capacity	48000 BTU/h
Weight	Varies by model.

Summary

Unit Dimensions

Dimensional Views Overview

Displays unit dimensions from top, side, end, and back views.

Parts Arrangement

LGT Parts Arrangement

Illustrates components of LGT models for identification.

LCT Parts Arrangement

Illustrates components of LCT models for identification.

Unit Support and Mounting

Unit Support Requirements

Downflow Discharge Mounting

Installers Roof Mounting Frame

Horizontal Discharge Mounting

Condensate Drain Management

Condensate Drain Connection Methods

Rear Drain Connection Modification

Bottom Condensate Drain Connection

Gas Piping Connection Guide

Guidance on connecting gas supply lines to the unit.

Gas Piping Pressure Testing

Gas Piping Pressure Test Procedure

Procedures for testing gas piping for leaks and safety.

High Altitude and Mobile App Usage

Power Supply Electrical Connections

Instructions for connecting the unit's main power supply.

Electrical Connections - Control Wiring

Thermostat Mode Operation

Zone Sensor Mode Operation

Hot Gas Reheat Operation

Setup and operational procedures for the hot gas reheat function.

Blower Operation and Adjustments

Blower Operation and Testing

Determining and Adjusting Unit CFM

Procedures for measuring and setting the unit's airflow (CFM).

Cooling Start-Up Procedures

Cooling Operation Initiation

Steps to initiate full load cooling operation via the service app.

Refrigerant Charge and Check

Procedures for checking and adjusting refrigerant charge.

Compressor Control Systems

Compressor Protection Switches

Details on compressor protection switches and controls.

Diagnostic Sensors Information

Thermistors for System Monitoring

Information on thermistors used for system monitoring and protection.

Cooling Operation Modes

Two-Stage Thermostat Cooling

Three-Stage Thermostat;Room Sensor Cooling

Gas Heat Start-Up Procedures

Initial Unit Operation Steps

Steps for starting the gas heating unit safely.

Gas Valve Operation Instructions

Instructions for operating the gas control valve.

Heating Sequence and Diagnostics

Heating sequence, ignition diagnostics, limit controls, and adjustments.

Electric Heat Start-Up

Procedures for starting electric heat operation.

SCR Electric Heat Controller Details

Details on the SCR electric heat controller functionality.

Hot Gas Reheat Start-Up and Operation

General Reheat Operation Overview

Reheat Coil Solenoid Valve Function

Reheat Setpoint Adjustment

Reheat Operation Check-Out

Service and Maintenance Procedures

Air Filter Maintenance

Burner Maintenance and Cleaning

Procedures for cleaning and inspecting gas burners.

Component Service Procedures

Combustion Air Inducer Service

Flue Box and Coil Cleaning

Supply Air Blower Wheel Inspection

K-UVC Light Installation and Maintenance

Factory-Installed UVC Light Details

Annual UVC Lamp Replacement

Lamp Disposal and Fuse Information

Replacement Fuse Size Specifications

Table listing correct fuse sizes for various model and voltage combinations.

Replacement Fuse Tables

LGT036 Replacement Fuses

LGT048 Replacement Fuses

LGT060 Replacement Fuses

LGT072 Replacement Fuses

LCT036 Replacement Fuses

Fuse specifications for LCT036 models.

LCT048 Replacement Fuses

LCT060 Replacement Fuses

LCT072 Replacement Fuses

Factory Unit Controller Settings

BACnet Settings Configuration

Room Sensor;Gateway Settings

LonTalk Settings Configuration

Hot Gas Reheat Settings

Configuration ID 1 Settings

Economizer Configuration Options

Power Exhaust Configuration Options

Power Exhaust Control Configuration Options

Configuration ID 2 Settings

Air Flow Proving Switch Configuration

Dirty Filter Switch Configuration

Electric Heat Configuration

Unit Start-Up Report

Inspections and Checks

Checklist for initial unit inspection and verification.

Cooling System Checks

Procedures for checking cooling system operation.

Blower System Checks

Procedures for checking blower operation and alignment.

Electric Heating Checks

Procedures for checking electric heating system functionality.

Gas Heating Checks

Procedures for checking gas heating system functionality.

Accessory System Checks

Checks for optional unit accessories like power exhaust.

Control Type Verification

Verification of the unit's control type and settings.