Lennox LGT092H 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
CAUTION
As with any mechanical equipment, contact with
sharp sheet metal edges can result in personal
injury. Take care while handling this equipment and
wear gloves and protective clothing.
Table of Contents
Options / Accessories . . . . . . . . . . . . . . . . . . . . . Page 2

Blower Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 8
Electrical Data . . . . . . . . . . . . . . . . . . . . . . . . . . Page 11
Parts Arrangement . . . . . . . . . . . . . . . . . . . . . . . Page 13
I-Unit Components . . . . . . . . . . . . . . . . . . . . . . . Page 14
II-Placement and Installation . . . . . . . . . . . . . . . Page 29
III-Charging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 29
IV-Start Up - Operation . . . . . . . . . . . . . . . . . . . . Page 34
V-System Service Checks . . . . . . . . . . . . . . . . Page 36
VI-Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . Page 39
VII-Accessories . . . . . . . . . . . . . . . . . . . . . . . Page 39
VIII-Direct Drive Supply Air Blower . . . . . . . . . . Page 49
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
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.
       
(CTO) with a wide selection of factory-installed options.

         
sections are designed with aluminized steel tube heat ex-
changers with stainless steel as an option.

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 tenton
units with all available blower options:

LGT12w are equipped with all aluminum condenser
coils with one two stage scroll compressor and one


        
nameplate. Operating pressures and pressure switch set-
-

󰀨-
ent energy management thermostat control systems with
-
tions 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

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.

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.
LGT SERIES
7.5 to 12.5 ton

LGT092H through 150H

Lennox LGT092H Specifications

General

Model	LGT092H
Type	Air Handler
Phase	1
Refrigerant	R-410A
Heating Capacity	92000 BTU
Configuration	Upflow/Horizontal
Voltage	208/230V

Summary

UNIT INFORMATION

OPTIONS / ACCESSORIES

COOLING SYSTEM

Lists cooling system options and accessories.

HEATING SYSTEM

Lists heating system options and accessories.

BLOWER - SUPPLY AIR

Lists supply air blower options.

CABINET

Lists cabinet related options.

CONTROLS

Lists control system options and accessories.

INDOOR AIR QUALITY

Lists indoor air quality sensor options.

ELECTRICAL

Lists electrical component options.

ECONOMIZER

Lists economizer options and accessories.

OUTDOOR AIR

Lists outdoor air related options.

POWER EXHAUST

Lists power exhaust options.

HUMIDITROL® CONDENSER REHEAT OPTION

Lists dehumidification options.

ROOF CURBS

Lists roof curb options.

CEILING DIFFUSERS

Lists ceiling diffuser options.

SPECIFICATIONS

General Data

Provides general unit specifications and performance data.

Cooling Performance

Details cooling capacity, airflow, and efficiency.

Refrigerant Charge

Specifies refrigerant type and quantities.

Gas Heating Options Available

Lists available gas heating input options.

Compressor Type (number)

Identifies compressor types used in units.

Outdoor Coils

Details outdoor coil specifications.

Outdoor Coil Fans

Details outdoor fan motor and size specifications.

Indoor Coil

Details indoor coil specifications.

Indoor Blower

Details indoor blower motor and size specifications.

Filters

Specifies filter type and size.

Electrical characteristics

Lists electrical operating parameters.

Gas Heat

Details gas heating performance specifications.

HIGH ALTITUDE DERATE

Explains derating for high altitude installations.

BLOWER DATA

POWER EXHAUST FAN PERFORMANCE

Details power exhaust fan static pressure and airflow.

ELECTRICAL DATA

7.5 ΤΟΝ

Electrical data for 7.5 ton units.

8.5 ΤΟΝ

Electrical data for 8.5 ton units.

10 ΤΟΝ

Electrical data for 10 ton units.

12.5 ΤΟΝ

Electrical data for 12.5 ton units.

PARTS ARRANGEMENT

CONTROL BOX PARTS ARRANGEMENT

Identifies components within the control box.

I-UNIT COMPONENTS

A-Control Box Components

Lists main control box components.

1-Disconnect Switch S48 (Optional)

Describes the optional disconnect switch.

2-Control Transformer T43 (Re-Heat Units)

Details the control transformer for reheat units.

3-Control Transformer T1

Details the main control transformer.

4-Outdoor Fan Relay K10, K68

Describes outdoor fan relays.

5-Outdoor Fan Capacitors C1, C2

Describes outdoor fan capacitors.

6-C. A. I. Transformers T3 575V Units

Describes 575V unit transformers.

7-Compressor Contactor K1, K2

Describes compressor contactors.

8-Burner Controls A3

Describes the burner control module.

9-Power Exhaust Relay K65 (PED units)

Describes power exhaust relay.

10-Unit Controller A55

Describes the main unit controller.

11-Terminal Block TB13

Describes the line voltage terminal block.

12-Wireless Antenna

Describes the wireless antenna location.

Temperature Sensors

Relative Humidity Sensor - Optional

Describes the optional humidity sensor.

Enthalpy Sensor - Optional

Describes the optional enthalpy sensor.

Economizer Differential Pressure Sensor - Optional

Describes the economizer pressure sensor.

PLUMBING, COMPRESSOR AND REFRIGERANT CIRCUITS DETAIL

B-Cooling Components

Details cooling circuit components.

1-Compressors B1, B2

Describes the unit's scroll compressors.

2-Crankcase Heaters HR1, HR2

Describes compressor crankcase heaters.

3-High Pressure Switches S4, S7

Describes high pressure safety switches.

4-Filter Drier

Describes the refrigerant filter drier.

5-Low Pressure Switches S87, S88

Describes low pressure safety switches.

6-Condenser Fans B4 and B5

Describes condenser fans.

7-Temperature Sensors RT46, RT47, RT48 & RT49

Describes refrigerant circuit temperature sensors.

C-Blower Compartment

1-Blower Wheels

Describes the type of blower wheels used.

2-Indoor Blower Motor B3

Describes the indoor blower motor.

A-Blower Operation

Explains how the blower operates.

B-Blower Access

Details how to access the blower assembly.

D-GAS HEAT COMPONENTS

1-Control Box Components A3, A55, T3, K13

Lists gas heat control box components.

Burner Ignition Control A3

Describes the burner ignition control module.

2-Heat Exchanger (Figure 14)

Describes the heat exchanger assembly.

3-Gas Heat Exchanger Inserts (Some LGT Units)

Describes optional heat exchanger inserts.

4-Burner Box Assembly (Figure 16)

Describes the burner box assembly.

5-Primary High Temperature Limits S10

Describes the primary high temperature limit switch.

6-Flame Roll-out Limit S47

Describes the flame roll-out limit switch.

7-Combustion Air Prove Switch S18

Describes the combustion air prove switch.

8-Combustion Air Inducer B6

Describes the combustion air inducer motor.

9-Combustion Air Motor Capacitor C3

Describes the combustion air inducer motor capacitor.

10-Gas Valves GV1

Describes the gas valve.

11-Spark Electrodes

Describes the spark electrode assemblies.

12-Flame Sensors

Describes the flame sensor.

II-PLACEMENT AND INSTALLATION

A-Refrigerant Charge and Check

Details procedures for checking refrigerant charge.

IV-START-UP - OPERATION

A-Preliminary and Seasonal Checks

Outlines pre-start-up checks.

B-Cooling Start-up See figure 23

Provides steps for initiating cooling operation.

C-Heating Start-up

Provides steps for initiating heating operation.

Placing Furnace In Operation

Details the sequence for placing the furnace in operation.

Turning Off Gas to Appliance

Details the procedure for shutting off gas.

D-Safety or Emergency Shutdown

Describes safety and emergency shutdown procedures.

V-SYSTEMS SERVICE CHECKS

A-Heating System Service Checks

Details service checks for the heating system.

1-Gas Piping

Covers gas piping requirements and checks.

2-Testing Gas Piping

Details procedures for testing gas piping.

3-Testing Gas Supply Pressure

Outlines how to test gas supply pressure.

4-Check and Adjust Manifold Pressure

Details manifold pressure checks and adjustments.

5-Proper Gas Flow

Covers checking proper gas flow to burners.

6-Inshot Burner

Details inshot burner inspection and service.

7-Spark Electrode Gap

Details spark electrode gap checks.

8-Heat Exchanger

Details heat exchanger access and removal.

9-Flame Sensing

Describes flame sensing operation and measurement.

VI-MAINTENANCE

A-Filters

Details filter inspection, cleaning, and replacement.

B-Lubrication

States that motors are pre-lubricated.

C-Supply Air Blower Wheel

Details inspection of the supply air blower wheel.

D-Evaporator Coil

Details evaporator coil inspection and cleaning.

E-Condenser Coil

Details condenser coil inspection and cleaning.

F-Electrical

Covers electrical checks during maintenance.

VII-ACCESSORIES

A-Mounting Frames

Details roof mounting frame options.

B-LP / Propane Kit

Describes the LP/propane conversion kit.

C-Dirty Filter Switch S27

Describes the dirty filter switch function.

D-Transitions

Details optional supply/return transitions.

E-LAOAD(M) Outdoor Air Dampers (all units)

Describes outdoor air damper options.

F-Supply and Return Diffusers (all units)

Describes optional diffusers.

G-Blower Proving Switch S52

Describes the blower proving switch.

H-Economizer (all units) (Field or Factory Installed)

Free Cooling Mode

Explains the free cooling operation modes.

Unit Controller Settings

Details how to adjust unit controller settings for economizer.

I-Gravity Exhaust Dampers

Gravity Exhaust Dampers

Describes gravity exhaust dampers and their function.

J-LAPEF Power Exhaust Fans

LAPEF Power Exhaust Fans

Describes LAPEF power exhaust fans.

UNIT SYSTEMS AND OPTIONS

K-Control Systems

Describes the A55 Unit Controller and its functions.

L-Indoor Air Quality (CO2) Sensor A63

Describes the CO2 sensor function.

M-Drain Pan Overflow Switch S149 (optional)

Describes the drain pan overflow switch.

N-Smoke Detectors A17 and A64

Describes the smoke detector options.

O-Factory Installed-Hot Gas Reheat (optional)

Describes the hot gas reheat system for dehumidification.

P-Optional Cold Weather Kit (Canada only)

Describes the optional cold weather kit.

GAS HEAT SEQUENCE OF OPERATION LGT092H-150H

First Stage Heat:

Details the sequence for first stage heating.

Second Stage Heat:

Details the sequence for second stage heating.

End of Second Stage Heat:

Describes the end of second stage heating.

End of First Stage Heat:

Describes the end of first stage heating.

Optional Low Ambient Kit:

Describes the low ambient kit operation.

LGT092H-150H SEQUENCE OF OPERATION

Power:

Explains power supply and distribution.

Blower Operation:

Details blower operation sequence.

Economizer Operation:

Details economizer operation sequence.

1st Stage Cooling (compressor B1)

Describes the sequence for 1st stage cooling.

2nd Stage Cooling (compressor B2 is energized)

Describes the sequence for 2nd stage cooling.

3nd Stage Cooling (compressor B1 in full load and compressor 2 is energized)

Describes the sequence for 3rd stage cooling.

DIRECT DRIVE BLOWER SEQUENCE OF OPERATION / TROUBLESHOOTING

Blower Operation:

Details blower operation sequence.

Blower Fault Sequence Direct Drive Motor - No S52:

Outlines fault sequence without S52 switch.

Blower Fault Sequence Direct Drive Motor - With S52 (If Configured):

Outlines fault sequence with S52 switch.

Failure Handling/Troubleshooting:

Provides steps for troubleshooting blower failures.