Lennox LGT102H4E 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


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 LGT102H4E Specifications

General

Model	LGT102H4E
Type	Air Handler
Voltage	208/230V
Phase	1
Refrigerant	R-410A
Airflow Range	400-1200 CFM
Motor Type	ECM
Cabinet Insulation	Foil-faced
Cooling Capacity	24, 000 BTU
Heating Capacity	24, 000 BTU
Configuration	Horizontal
Maximum External Static Pressure	0.8 in. w.g.
Stages	Single

Summary

OPTIONS / ACCESSORIES

SPECIFICATIONS

General Data

General unit specifications including tonnage, efficiency, and model numbers.

Cooling Performance

Cooling capacity, airflow, and power consumption details.

Refrigerant Charge

Refrigerant type and charge amounts for different configurations.

VAV MODELS

Heat Input Type

Details heat input types and number of stages.

Gas Heating Performance

Performance data for gas heating, including input, output, and efficiency.

HIGH ALTITUDE DERATE

BLOWER DATA

FACTORY INSTALLED OPTIONS/FIELD INSTALLED ACCESSORY AIR RESISTANCE - in. w.g.

POWER EXHAUST FAN PERFORMANCE

ELECTRICAL DATA

7.5 ΤΟΝ

Electrical data specific to the 7.5 ton model.

8.5 ΤΟΝ

Electrical data specific to the 8.5 ton model.

10 ΤΟΝ

Electrical data specific to the 10 ton model.

12.5 ΤΟΝ

Electrical data specific to the 12.5 ton model.

I-UNIT COMPONENTS

ELECTROSTATIC DISCHARGE (ESD) Precautions and Procedures

CAUTION (Electrostatic discharge)

A-Control Box Components

10-Unit Controller A55

Functions and features of the A55 Unit Controller.

PLUMBING, COMPRESSOR AND REFRIGERANT CIRCUITS DETAIL

B-Cooling Components

Description of cooling system components.

WARNING (Electrical shock hazard)

Critical safety warning regarding compressor handling.

1-Compressors B1, B2

Details of the two scroll compressors.

C-Blower Compartment

IMPORTANT (Compressor two)

Critical note regarding compressor two and proper phasing.

A-Blower Operation

How the blower operates under different control modes.

WARNING (Make sure unit is installed)

Safety warnings for unit installation and operation.

B-Blower Access

DIRECT DRIVE PARAMETER SETTINGS - 581102-01

BLOWER SMOKE CFM

BLOWER HEATING HIGH CFM

BLOWER HEATING LOWCFM

BLOWER COOLING HIGH CFM

BLOWER COOLING LOW CFM

BLOWER VENTILATION CFM

SETUP > TEST & BALANCE > DAMPER

Menu path for damper setup and testing.

BLOWER HIGH CFM DAMPER POS %

BLOWER LOW CFM DAMPER POS %

POWER EXHAUST DAMPER POS %

POWER EXHAUST DEADBAND %

FREE COOLING STAGE-UP DELAY

CAUTION (The BLOWER CALIBRATION process)

Caution regarding the blower calibration process.

IMPORTANT - The default value for Cooling Low motor speed

D-GAS HEAT COMPONENTS

WARNING (Shock hazard)

Critical safety warning regarding spark-related components.

Burner Ignition Control A3

Description of the burner ignition control.

NORMAL IGNITION SEQUENCE - TIMINGS NOMINAL

RETRIALS - IGNITION ATTEMPT SEQUENCE - TIMINGS NOMINAL

2-Heat Exchanger (Figure 14)

Description of the heat exchanger assembly.

3-Gas Heat Exchanger Inserts (Some LGT Units)

TYPICAL GAS BURNER ASSEMBLY

Orifice

5-Primary High Temperature Limits S10

Description of the primary high temperature limit switch.

6-Flame Roll-out Limit S47

7-Combustion Air Prove Switch S18

Description of the combustion air prove switch.

8-Combustion Air Inducer B6

Description of the combustion air inducer.

10-Gas Valves GV1

Description of the two-stage gas valve.

TABLE 7

11-Spark Electrodes

Description and installation of spark electrodes.

12-Flame Sensors

Description of flame sensors and their operation.

II-PLACEMENT AND INSTALLATION

A-Refrigerant Charge and Check

Procedure for checking and charging refrigerant.

WARNING-Do not exceed nameplate charge

Critical safety warning regarding refrigerant charge limits.

IMPORTANT - Charge unit in standard cooling mode

IV-START-UP - OPERATION

A-Preliminary and Seasonal Checks

Pre-start-up checks for installation and condition.

B-Cooling Start-up See figure 23

Procedure for starting the cooling operation.

C-Heating Start-up

Procedure for starting the heating operation.

WARNING (Danger of explosion)

Critical safety warning regarding gas heating.

IMPORTANT

Placing Furnace In Operation

Turning Off Gas to Appliance

Procedure for turning off gas to the appliance.

D-Safety or Emergency Shutdown

Procedure for safety or emergency shutdown.

V-SYSTEMS SERVICE CHECKS

A-Heating System Service Checks

Procedures for checking the heating system.

1-Gas Piping

Guidelines for gas piping installation and checks.

2-Testing Gas Piping

Procedure for testing gas piping for leaks.

3-Testing Gas Supply Pressure

Procedure for testing gas supply pressure.

4-Check and Adjust Manifold Pressure

Procedure for checking and adjusting manifold pressure.

Manifold Adjustment Procedure

Step-by-step procedure for manifold adjustment.

CAUTION (Disconnect heating demand)

Caution regarding disconnecting heating demand.

5-Proper Gas Flow

6-Inshot Burner

Description and maintenance of inshot burners.

7-Spark Electrode Gap

Procedure for checking and setting the spark electrode gap.

8-Heat Exchanger

Procedure for accessing or removing the heat exchanger.

9-Flame Sensing

Explanation of flame sensing and measurement.

VI-MAINTENANCE

A-Filters

Information on filter inspection, cleaning, and replacement.

WARNING (Electric shock hazard)

Critical safety warning before performing maintenance.

C-Supply Air Blower Wheel

D-Evaporator Coil

E-Condenser Coil

F-Electrical

Electrical checks for maintenance.

VII-ACCESSORIES

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

Free Cooling Mode

Description of the free cooling mode operation.

Unit Controller Settings

ECONOMIZER MODES AND SETPOINT

TEMP

Remote

ENTH

GLOBAL

K-Control Systems

L-Indoor Air Quality (CO2) Sensor A63

M-Drain Pan Overflow Switch S149 (optional)

N-Smoke Detectors A17 and A64

O-Factory Installed-Hot Gas Reheat (optional)

Description of the hot gas reheat system.

UVC ASSEMBLY

R- UVC Light

Information on the UVC light kit.

Factory-Installed UVC Light

Details on factory-installed UVC lights.

Annual Lamp Replacement

Procedure for annual UVC lamp replacement.

WARNING (Personal Burn Hazard)

Critical safety warning regarding hot lamps.

INSTALL LAMP IN HOLDER CLIPS

2- Check Lamp

LED(s) not illuminated

Lamp Disposal

Proper Clean-up Technique in Case of Lamp Breakage

Maintenance

General maintenance recommendations.

Do not use a vacuum cleaner

Warning against using vacuum cleaners for maintenance.

For all maintenance, contact a qualified HVAC technician

Recommendation to use qualified technicians for maintenance.

Unintended use of the unit or damage

Warning about unintended use and UVC radiation hazard.

▲ DANGER

UVC LIGHT TROUBLESHOOTING - POWER

Troubleshooting steps for when the UVC lamp is not operating.

UVC LIGHT TROUBLESHOOTING - LAMP

Troubleshooting steps for when UVC lamp LEDs are not lit.

VIII-Direct Drive Supply Air Inverter

A-Set Blower Speed

Procedure for setting the supply air blower speed.

Blower CFM Design Specifications

Heating

Cooling High

Cooling Medium

Cooling Low

Ventilation

2- Use the following menu

Menu navigation for entering blower CFM.

SETUP > TEST & BALANCE > BLOWER

Menu path for blower setup and testing.

3- Once all four speeds are entered

4 - Measure the static pressure

Procedure for measuring static pressure.

5- Enter the RPM

Procedure for entering RPM to reach design CFM.

B-Set Damper Minimum Position

Procedure for setting minimum damper positions.

IX-Staged Supply Air Operation

A-Two-Stage Thermostat

Cooling operation summary for two-stage thermostats.

Y2 Demand -

B-Three-Stage Thermostat OR Zone Sensor

1-Economizer With Outdoor Air Suitable

Operation when economizer is suitable.

Y1 Demand -

2-No Economizer or Outdoor Air Not Suitable

Y1 Demand

Y2 Demand

Y3 Demand

X-Wiring Diagrams and Sequence of Operation

GAS HEAT FOR LGT092H-150H UNITS Y and G Voltage

GAS HEAT FOR LGT092H-150H UNITS J Voltage

GAS HEAT SEQUENCE OF OPERATION LGT092H-150H

First Stage Heat:

Sequence of operation for first stage heat.

Second Stage Heat:

Sequence of operation for second stage heat.

End of Second Stage Heat:

End of operation for second stage heat.

End of First Stage Heat:

End of operation for first stage heat.

Optional Low Ambient Kit:

ECONOMIZER

KEY LIST

Cooling Diagram with Higher SCCR

WARNING

Safety warnings for electrical work.

LGT092H-150H SEQUENCE OF OPERATION

Power:

Sequence of operation for power supply.

Economizer Operation:

Sequence of operation for the economizer.

1st Stage Cooling (compressor B1)

Sequence of operation for first stage cooling.

2nd Stage Cooling (compressor B2 is energized)

Sequence of operation for second stage cooling.

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

Sequence of operation for third stage cooling.

DIRECT DRIVE BLOWER SEQUENCE OF OPERATION / TROUBLESHOOTING

Blower Operation:

Sequence of operation for direct drive blower.

Blower Fault Sequence Direct Drive Motor - No S52:

Troubleshooting for blower faults without S52.

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

Troubleshooting for blower faults with S52.

Failure Handling/Troubleshooting:

General troubleshooting steps for blower failures.