Lennox LGH092H4B

Corp. 1008-L2
LGH SERIES
Service Literature
7.5 to 12.5 ton
38.1 to 70.3 kW
Revised 5/2015
LGH092H through 152U
The LGH092H, 094U, 102H, 120H, 122U, 150S and
152U units are configure to order units (CTO) with a wide
selection of factory-installed options. Units are avail
able in 130,000, 180,000 Btuh or 240,000 Btuh (38.1,
52.7 or 70.3 kW) heating inputs. Gas heat sections are
designed with Lennox' aluminized steel tube heat ex
changers with stainless steel as an option.
Cooling capacities range from 7.5 to 12.5 tons (38.1 to
70.3 kW). All units are equipped with two compressors.
Ultra-high efficiency units are available with an optional di
rect drive blower or belt drive blower equipped with a sup
ply air inverter. Standard and high efficiency units are
available with a belt drive blower equipped with an option
al supply air inverter. 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 ten-
ton units with all available blower options:
LGH120H4B High Efficiency Belt Drive
LGH120H4M High Efficiency Belt Drive with Inverter
LGH122U4M Ultra High Efficiency Belt Drive with Inverter
LGH122U4E Ultra High Efficiency Direct Drive
Note - Ten-ton units are available in high and ultra high effi
ciencies only.
Standard and high efficiency units come standard with a
lightweight, all-aluminum condenser coil; optional, fin/
tube condenser coils are available. Ultra-high efficiency
units come standard with a tube/fin condenser coil.
Ultra high efficiency units come standard with two single-
speed compressors plumbed in tandem to form a single re
frigerant circuit.
Units are also designed for R410A refrigerant. See unit
nameplate. Operating pressures and pressure switch set
tings are significantly higher than R22 charged units. Ser
vice equipment must be rated for R410A.
Standard and high efficiency units offer mechanical cooling
down to 0°F when properly equipped. Ultra-high efficiency
units offer mechanical cooling down to 40°F.
All LGH units are designed to accept any of several differ
ent energy management thermostat control systems with
minimum field wiring. Factory or field provided control op
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 by
qualified service technicians only. All specifications are
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.
3
3
Table of Contents
Options / Accessories Page 2.....................
Specifications Page 8............................
Blower Tables Page 14............................
Electrical Data Page 19...........................
Parts Arrangement Page 25.......................
I-Unit Components Page 28.......................
II-Placement and Installation Page 47...............
III-Charging Page 47..............................
IV-Start Up - Operation Page 55....................
V-System Service Checks Page 57................
High Altitude Page 59.........................
VI-Maintenance Page 59..........................
VII-Accessories Page 60..........................
VIII-Belt Drive Supply Air Inverter Page 67...........
IX-Direct Drive Supply Air Blower Page 70...........
X-Staged Supply Air Operation Page 71.............
XI-Wiring and Operation Sequence Page 72.........
WARNING
Improper installation, adjustment, alteration, service
or maintenance can cause property va, personal in
jury 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 in
jury. Take care while handling this equipment and
wear gloves and protective clothing.
© 2015

Lennox LGH092H4B Specifications

General

Brand	Lennox
Model	LGH092H4B
Category	Air Handlers
Language	English

Summary

UNIT INFORMATION

WARNING

Safety warning about improper installation, adjustment, alteration, service, or maintenance.

CAUTION

Caution regarding sharp sheet metal edges and protective clothing.

SPECIFICATIONS - GAS HEAT - 094 U, 122 U, 152 U

Gas Heating Performance

ELECTRICAL DATA

7.5 HIGH EFFICIENCY (R-410 A) LGH092 H4

Electrical data for 7.5 Ton High Efficiency LGH092H4.

10 HIGH EFFICIENCY (R-410 A) LGH120 H4

Electrical data for 10 Ton High Efficiency LGH120H4.

8.5 HIGH EFFICIENCY (R-410 A) LGH102 H4

Electrical data for 8.5 Ton High Efficiency LGH102H4.

12.5 STANDARD EFFICIENCY (R-410 A) LGH150 S4

Electrical data for 12.5 Ton Standard Efficiency LGH150S4.

ELECTRICAL DATA DIRECT DRIVE

7.5 LGH094 U4 E

Electrical data for 7.5 Ton Direct Drive LGH094U4E.

12.5 LGH152 U4 E

Electrical data for 12.5 Ton Direct Drive LGH152U4E.

10 LGH122 U4 E

Electrical data for 10 Ton Direct Drive LGH122U4E.

ELECTRICAL DATA BELT DRIVE

7.5 LGH094 U4 M

Electrical data for 7.5 Ton Belt Drive LGH094U4M.

10 LGH122 U4 M

Electrical data for 10 Ton Belt Drive LGH122U4M.

PARTS ARRANGEMENT - 092 H, 102 H, 120 H, 150 S

ALL-ALUMINUM COIL SYSTEM

PARTS ARRANGEMENT - 094 U, 122 U, 152 U

FINTUBE COIL

CONTROL BOX PARTS ARRANGEMENT - STANDARD AND HIGH EFFICIENCY NON-CE UNITS

Control box parts for standard/high efficiency non-CE units.

PARTS ARRANGEMENT

CONTROL BOX PARTS ARRANGEMENT - ULTRA HIGH EFFICIENCY NON-CE UNITS

Control box parts for ultra high efficiency non-CE units.

CONTROL BOX PARTS ARRANGEMENT - CE UNITS

Control box parts for CE units.

PLUMBING, COMPRESSOR AND REFRIGERANT CIRCUITS DETAIL

(HIGH EFFICIENCY ALL-ALUMINUM OUTDOOR COIL)

(OPTIONAL STANDARD EFFICIENCY FINTUBE COIL)

(OPTIONAL ULTRA HIGH EFFICIENCY UNITS WITH FINTUBE COIL)

B-Cooling Components

1-Compressors B1, B2

Details on standard, high, and ultra high efficiency compressors.

3-High Pressure Switches S4, S7

Description and function of high pressure switches.

B-Cooling Components

4-Low Ambient Switches S11, S84

Details on low ambient switches and their operation.

7-Low Pressure Switches S87, S88

Description and function of low pressure switches.

B-Cooling Components

9-Freezestats S49 and S50

Details on freezestats and their function.

10-Temperature Sensors RT37 and RT38

11-Pressure Transducer A185

D-GAS HEAT COMPONENTS

Burner Ignition Control A3

Details on the burner ignition control.

HEAT EXCHANGER ASSEMBLY

HEAT EXCHANGER ASSEMBLY

BURNER BOX ASSEMBLY

BURNER BOX ASSEMBLY

TYPICAL GAS BURNER ASSEMBLY

BURNER SUPPORT

D-GAS HEAT COMPONENTS (Continues)

6-Flame Roll-out Limit S47

Description of the flame roll-out limit S47.

7-Combustion Air Prove Switch S18

Details on the combustion air prove switch S18.

8-Combustion Air Inducer B6

GAS VALVE REGULATION FOR LGH UNITS

WHITE-RODGERS 36 C76 GAS VALVE

HONEYWELL VR8305 VR8205 GAS VALVE

II-PLACEMENT AND INSTALLATION

III-CHARGING

Procedures for refrigerant charging and checking.

A-Refrigerant Charge and Check - All-Aluminum Coil

Refrigerant charge verification for all-aluminum coils.

IMPORTANT - Charge unit in standard cooling mode.

Key instruction for charging in standard cooling mode.

TABLE 5

TABLE 6

LGHLCH102 H All-Aluminum Coil Normal Operating Pressures - TXV

TABLE 7

LGHLCH120 H All-Aluminum Coil Normal Operating Pressures - TXV

TABLE 8

LGHLCH150 S All-Aluminum Coil Normal Operating Pressures - TXV

LGHLCH092 H All-Aluminum Coil Charging Curves

LGHLCH102 H All-Aluminum Coil Charging Curves

LGHLCH120 H All-Aluminum Coil Charging Curves

LGHLCH150 S All-Aluminum Coil Charging Curves

Outdoor Temperature (F)

Charging curves based on outdoor temperature.

B-Refrigerant Charge and Check - FinTube Coil - TXV

LGHLCH092 H, 102 H, 120 H, 150 S

Refrigerant charge check for fin/tube coil TXV units.

TABLE 9

TABLE 10

TABLE 11

TABLE 12

TABLE 13

TABLE 14

TABLE 15

LGHLCH150 S FinTube Coil - TXV

TABLE 16

LGHLCH150 S FinTube Coil Hot Gas Reheat - TXV

Charge Verification - Approach Method - AHRI Testing

(FinTube Coil Continued)

Charge verification using approach method.

TABLE 17

F-Refrigerant Charge and Check - FinTube Coil & RFC

LGHLCH150 S

Refrigerant charge check for LGH/LCH150S Fin/Tube Coil & RFC.

TABLE 18

LGHLCH150 S Normal Operating Pressures - FinTube - RFC

G-Refrigerant Charge and Check - FinTube Coil & TXV

LGHLCH094 U, 122 U, 152 U

Refrigerant charge check for 094U, 122U, 152U units.

TABLE 19

TABLE 20

TABLE 21

Charge Verification - Approach Method - AHRI Testing

Charge verification using approach method.

TABLE 22

IV-START-UP - OPERATION

A-Preliminary and Seasonal Checks

Preliminary and seasonal checks before operation.

B-Cooling Start-up See figure 34, 35 or 36 for Circuits

Procedures for starting up the cooling system.

REFRIGERANT STAGES - All-Aluminum Coil

REFRIGERANT CIRCUITS - FinTube Coil

REFRIGERANT STAGES - 094 U, 122 U, 152 U TRADITIONAL FINTUBE COIL

C-Heating Start-up

FOR YOUR SAFETY READ BEFORE LIGHTING

Safety instructions before lighting the unit.

Placing Furnace In Operation

Procedure for placing the furnace into operation.

D-Safety or Emergency Shutdown

Steps for safety or emergency shutdown.

V-SYSTEMS SERVICE CHECKS

A-Heating System Service Checks

Service checks for the heating system.

1-Gas Piping

2-Testing Gas Piping

3-Testing Gas Supply Pressure

How to test gas supply pressure.

4-Check and Adjust Manifold Pressure

Checking and adjusting manifold pressure.

V-SYSTEMS SERVICE CHECKS (Continues)

5-Proper Gas Flow

Checking for proper gas flow to burners.

7-Spark Electrode Gap

9-Flame Sensing

Information on flame sensing and current measurement.

ECONOMIZER

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

Overview of the optional economizer.

SEQUENCE OF OPERATION ECONOMIZER

Sequence of operation for the economizer.

Free Cooling Mode

POWER:

TABLE 24

L-Control Systems

The A55 Unit Controller provides all control function for the rooftop unit.

Overview of the A55 Unit Controller's capabilities.

M-Indoor Air Quality (CO2) Sensor A63

The indoor air quality sensor monitors CO2 levels and reports the levels to the A55 Unit Controller.

N-Drain Pan Overflow Switch S149 (optional)

The overflow switch is used to interrupt cooling operation when excessive condensate collects in the drain pan.

P-Factory Installed-Hot Gas Reheat (optional)

General

REHEAT MODE REFRIGERANT ROUTING

Diagram of refrigerant routing in reheat mode.

FIGURE 48

Diagram of reheat mode refrigerant routing.

COOLING MODE REFRIGERANT ROUTING

Diagram of refrigerant routing in cooling mode.

FIGURE 49

Diagram of cooling mode refrigerant routing.

L14 Reheat Coil Solenoid Valve

Reheat Setpoint

Check-Out

Procedure for testing hot gas reheat operation.

TABLE 25

VIII-Belt Drive Supply Air Inverter

The supply air inverter or variable frequency drive (VFD), is located in the compressor compartment.

Location and function of the supply air inverter (VFD).

INPUTS REQUIRED TO STAGE SUPPLY AIR BLOWER

Diagram showing inputs for staging supply air blower.

AWARNING

Electrical shock hazard warning for VFDs.

TABLE 27

MINIMUM AND MAXIMUM CFM 092 H, 102 H, 120 H, 150 S

X-Staged Supply Air Operation

This is a summary of cooling operation for both belt and direct drive blowers.

Summary of staged supply air operation.

A-Two-Stage Thermostat

Cooling operation with a two-stage thermostat.

B-Three-Stage Thermostat OR Zone Sensor

Cooling operation with three-stage thermostat or zone sensor.

TABLE 29

MINIMUM AND MAXIMUM CFM 094 U4 E, 122 U4 E, 152 U4 E

XI-Wiring Diagrams and Sequence of Operation

LGH092150 S & H - CONSTANT SUPPLY AIR, BELT DRIVE BLOWER

Wiring diagram and sequence for constant supply air belt drive.

LGH092150 S & H SEQUENCE OF OPERATION

1 st Stage Cooling (compressor B1)

Sequence of operation for 1st stage cooling.

2 nd Stage Cooling (compressor B2 is energized)

Sequence of operation for 2nd stage cooling.

LGH092152 U STAGED SUPPLY AIR, NO BYPASS, BELT DRIVE BLOWER

LGH092152 U M3 SEQUENCE OF OPERATION

Power:

Power supply sequence for M3 units.

Economizer Operation:

Sequence of operation for the economizer in M3 units.

1 st Stage Cooling (compressor B1 or B2)

Sequence of operation for 1st stage cooling in M3 units.

2 nd Stage Cooling (compressor B1 and B2 are energized)

Sequence of operation for 2nd stage cooling in M3 units.

GAS HEAT FOR LGH092150 UNITS

KEY

Key for components in the gas heat wiring diagram.

WIRING DIAGRAM

Wiring diagram for gas heat.

GAS HEAT SEQUENCE OF OPERATION LGH092150

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 First Stage Heat:

LGHLCH092-150 S & H STAGED SUPPLY AIR, NO BYPASS, BELT DRIVE BLOWER

LGHLCH092-150 S & H STAGED SUPPLY AIR, WITH BYPASS, BELT DRIVE BLOWER

LGHLCH092-152 U STAGED SUPPLY AIR, WITH BYPASS, BELT DRIVE BLOWER

SUPPLY AIR INVERTER - NO BYPASS SEQUENCE OF OPERATION

SUPPLY AIR INVERTER - WITH OPTIONAL FACTORY-INSTALLED BYPASS SEQUENCE OF OPERATION

OPERATION:

A96 FAULT SEQUENCE:

Fault sequence for A96 inverter with bypass.

BLOWER FAULT SEQUENCE Direct Drive Motor - No S52:

Fault sequence for direct drive motor without S52.

BLOWER FAULT SEQUENCE Direct Drive Motor - With S52 (If Configured):

Fault sequence for direct drive motor with S52.

LGHLCH092-152 U STAGED SUPPLY AIR, DIRECT DRIVE BLOWER

24 VAC POWER

DIRECT DRIVE BLOWER SEQUENCE OF OPERATION TROUBLESHOOTING

Blower Operation:

Sequence of operation for direct drive blower motor.

Blower Fault Sequence Direct Drive Motor - No S52:

Fault sequence for direct drive motor without S52.

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

Fault sequence for direct drive motor with S52.

Failure HandlingTroubleshooting:

Troubleshooting steps for blower failures.

TABLE 30

DIRECT DRIVE BLOWER MOTOR TROUBLESHOOTING

Troubleshooting table for direct drive blower motor issues.