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Lennox SGH120 User Manual

Lennox SGH120
60 pages
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©2019
SGH120 SHOWN
IMPORTANT
Supply air VFD motor rotation is controlled indepen
dently from scroll compressor rotation. See Cooling
Start-Up section for correct compressor rotation.
Compressor damage due to improper rotation is the
responsibility of the installer.
Table of Contents
Dimensions Page 2.................................
Parts Arrangements Page 5.........................
Shipping and Packing List Page 8....................
General Page 8....................................
Safety Page 8.....................................
Unit Support Page 9................................
Duct Connection Page 10............................
Rigging Unit For Lifting Page 10.......................
Condensate Drains Page 10..........................
Gas Piping Page 11.................................
Pressure Test Gas Piping Page 11.....................
RETAIN THESE INSTRUCTIONS FOR FUTURE REFERENCE
INSTALLATION
INSTRUCTIONS
SGH/SCH036 (3 TON)
SGH/SCH060 (5 TON)
SGH/SCH120 (10 TON)
SGH/SCH240 (20 TON)
ROOFTOP UNITS
507964-01
9/2019
Supersedes 507364-02
High Altitude Derate Page 12.........................
Optional Outdoor Air Hood Page 13....................
Electrical Connections Page 15.......................
Blower Operation and Adjustments Page 17............
Cooling Start-Up Page 29............................
Cooling Operation and Adjustments Page 31............
Gas Heat Start-Up Page 41...........................
Electric Heat Start-Up Page 43........................
Heating Operation and Adjustments Page 43............
MSAV
t Unit Start-Up Page 45........................
MSAV
t Operation Page 46..........................
Direct Drive Start-Up Page 47.........................
Hot Gas Reheat Startup Page 49......................
Economizer Start-Up Page 53.........................
Service Page 55....................................
Factory Control Parameter Settings Page 58............
Start-Up Report Page 60.............................
WARNING
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 licensed professional HVAC in
staller or equivalent, service agency, or the gas sup
plier
WHAT TO DO IF YOU SMELL GAS:
If the information in this manual is not
followed exactly, a fire or explosion
may result causing property damage,
personal injury or loss of life.
WARNING
Do not store or use gasoline or
other flammable vapors and liq
uids in the vicinity of this or any
other appliance.
Installation and service must be
performed by a qualified installer,
service agency or the gas supplier.
S Do not try to light any appliance.
S Extinguish any open flame.
S Do not touch any electrical switch; do not
use any phone in your building.
S Immediately call your gas supplier from a
neighbor's phone. Follow the gas suppli
er's instructions.
S If you cannot reach your gas supplier, call
the fire department.
S Leave the building immediately.
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Lennox SGH120 Specifications

General IconGeneral
BrandLennox
ModelSGH120
CategoryAir Conditioner
LanguageEnglish

Summary

Shipping and Packing List

Safety Precautions

Highlights electrical shock and refrigerant handling hazards.

Unit Support and Mounting

Gas Piping Installation

Connect Gas Piping - SG Units

Details gas piping connection procedures for SG units.

Pressure Test Gas Piping - SG Units

Explains how to pressure test gas piping for SG units.

High Altitude Derate and Gas Safety

Gas Safety Warnings

Warns about fire and explosion hazards related to gas.

Electrical Connections

Power Supply Connections

Details how to connect the unit's main power supply.

Control Wiring and Thermostat Installation

Covers wiring for thermostats and zone sensors.

Blower Operation and Adjustments

Blower Operation Modes

Explains blower operation based on thermostat settings and unit type.

Blower Performance Tuning

Determining Unit CFM

Steps to measure and set required blower airflow (CFM).

Belt Tension Adjustments

Guides on adjusting belt tension for optimal blower performance.

Cooling Start-Up Procedures

Preliminary Checks

Essential checks before initiating unit start-up.

Unit Start-Up Sequence

Step-by-step guide for starting the cooling system.

Three Phase Compressor Voltage Phasing

Important info on compressor phasing and rotation for three-phase units.

Cooling Operation and Adjustments

Refrigerant Charge and Check

Procedures for checking and adjusting refrigerant charge.

Compressor Controls and Gas Heat

Compressor Control Logic

Explains the operation of compressor controls and fan cycling.

Gas Heat Start-Up

Safety and procedure for lighting the gas furnace.

Heating Operation and Adjustments

Heating Sequence of Operation

Describes the sequence of events during heating operation.

MSAV™ Unit Start-Up

Design Specifications Entry

How to enter design CFM specifications into the Unit Controller.

Direct Drive Blower Start-Up

Hot Gas Reheat Start-Up and Operation

Reheat Check-Out and Operation Modes

Economizer Configuration and Settings

Economizer Operation Modes

Service and Maintenance

Unit Controller Settings

Staged Blower Configuration

Start-Up Report

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