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General| Category | Furnace |
|---|---|
| Manufacturer | Lennox |
| Ignition System | Hot Surface Ignition |
| Product Series | LGM |
| Fuel Type | Gas |
| Heating Stages | Single-Stage |
| Warranty | Limited Lifetime Heat Exchanger Warranty, 5-Year Parts Warranty |
General description of LGM156U to 300U units and their features.
Details factory and field installed options for the cooling system.
Details factory and field installed options for the heating system.
Details blower options including motors and drive kits.
Details factory and field installed control options for the unit.
Details various indoor air quality enhancement options.
Details electrical related options such as GFI outlets and disconnect switches.
Details factory and field installed economizer components and controls.
Details options for outdoor air intake and dampers.
Details the Humiditrol and Hot Gas Reheat option for SZVAV models.
Details cabinet related accessory options.
Details various roof curb options for unit installation.
Details optional ceiling diffusers for supply and return air.
General unit data, cooling capacities, and performance metrics.
Details refrigerant type and charge amounts for various circuits.
Lists available gas heating options and compressor types.
Details specifications for outdoor coils and fans.
Details specifications for indoor coils, blower, and drive selection.
Details the type and size of filters used in the unit.
Details electrical characteristics and voltage requirements.
General data, cooling performance for 15 & 17.5 Ton models.
Refrigerant charge details for 15 & 17.5 Ton models.
Gas heating options and compressor types for 15 & 17.5 Ton models.
Outdoor coil and fan specifications for 15 & 17.5 Ton models.
Indoor coil and blower specifications for 15 & 17.5 Ton models.
General data, cooling performance for 20 & 25 Ton models.
Refrigerant charge details for 20 & 25 Ton models.
Gas heating options and compressor types for 20 & 25 Ton models.
Outdoor coil and fan specifications for 20 & 25 Ton models.
Indoor coil and blower specifications for 20 & 25 Ton models.
Details gas heating performance, input, and output ratings.
Details thermal efficiency and gas supply connection requirements.
Information on derating units for high altitude installations.
Altitude derate for two-stage gas heat units.
Altitude derate for four-stage gas heat units.
Tables showing blower performance data at various static pressures.
Specifies minimum air volume requirements for different gas heat sizes.
Specifications for factory installed blower drive kits.
Air resistance values for factory installed options and accessories.
Performance data for the power exhaust fan.
Air resistance values for different ceiling diffuser types.
Air throw distance data for ceiling diffusers.
Electrical data for compressors and voltage for 13 Ton units.
Electrical data for outdoor fans and indoor blower (13 Ton).
MOCP and MCA values for 13 Ton units.
Electrical data for compressors and voltage for 17.5 Ton units.
Electrical data for outdoor fans and indoor blower (17.5 Ton).
MOCP and MCA values for 17.5 Ton units.
Electrical data for compressors and voltage for 20 Ton units.
Electrical data for outdoor fans and indoor blower (20 Ton).
MOCP and MCA values for 20 Ton units.
Electrical data for compressors and voltage for 25 Ton units.
Electrical data for outdoor fans and indoor blower (25 Ton).
MOCP and MCA values for 25 Ton units.
Diagram showing the arrangement of major unit components.
Safety precautions for handling electrical components and static discharge.
Description of the disconnect switch S48.
Description of the control transformer T1.
Description of the contactor transformer T18.
Details the function of TB13 terminal block.
Description of fuse blocks for outdoor fans and power exhaust.
Description and function of compressor contactors.
Description of the blower contactor K3.
Description of the transformer for the UVC lamp.
Description of the burner control modules A3 and A12.
Description of power exhaust relays K65 and K231.
Description of the VFD for blower speed control.
Description of the contactor for VFD bypass option.
Description of the relay for inverter start rotation control.
Details the functions and capabilities of the Unit Controller A55.
Description of control modules for additional compressor stages.
Information on return air, discharge air, and outdoor air temperature sensors.
Details the CO2 sensor for IAQ and its function.
Description of the VAV supply static pressure sensor.
Description of the indoor relative humidity sensor.
Description of optional enthalpy sensors.
Description of the pressure transducer for economizer control.
Description of the relay for second-stage power exhaust.
Description of transformers for 460V outdoor fans.
Description of fuse F61 for overcurrent protection.
Description of the overload relay for the blower motor.
Details about the scroll compressors used in the units.
Description of crankcase heaters for compressors.
Details high pressure switches and their operation.
Details low pressure switches and their operation.
Description of optional service valves.
Description of the filter drier's function in the refrigerant circuit.
Details about the condenser fans used in the units.
Description of the high temperature sensor S5.
Description of temperature thermistors for refrigeration circuits.
Description of the blower compartment location and access.
Details about the blower wheels used in the unit.
Description of the indoor blower motor and its specifications.
Important checks before unit installation and startup.
Procedure for accessing the blower assembly for service.
Procedure for determining and setting unit CFM.
Diagram showing locations for static pressure readings.
Instructions for adjusting blower belt tension and alignment.
Instructions for aligning pulleys when a belt tensioner is present.
Procedure for checking and measuring belt tension.
Reference to blower drive tables for field-supplied drives.
Description of control box components and safety warnings.
Details of the burner ignition control modules and LED codes.
Nominal timings for the normal ignition sequence.
Nominal timings for ignition attempt sequences with retrials.
Specific ignition control timing details.
Description and diagram of the heat exchanger assembly.
Details on the burner assembly, its components, and operation.
Description of primary high temperature limit switches.
Description of flame rollout limit switches.
Description of combustion air blower proving switches.
Description of combustion air inducer blowers.
Details of capacitors for combustion air blower motors.
Description of the two-stage redundant gas valves.
Procedures for charging and checking refrigerant levels.
Guidance on charging the unit in normal cooling mode.
Tables for determining pressures based on outdoor temperature.
Tables showing normal operating pressures for compressors.
Tables for determining approach temperatures for refrigerant circuits.
Essential checks before unit installation and startup.
Step-by-step procedure for initiating cooling operation.
Information on the number and type of refrigerant circuits.
Details on the correct refrigerant charge amount.
Procedure for safely starting the unit in heating mode.
Details on operating the Honeywell gas valve.
Procedure for safely shutting off gas supply to the unit.
Procedure for shutting down the unit in emergencies.
Procedures for servicing the heating system.
Details on gas piping installation, testing, and leak detection.
Procedure for testing and verifying gas supply pressure.
Procedure for checking and adjusting manifold pressure.
Procedure for checking gas flow to the burners.
Details on inshot burner inspection, cleaning, and flame viewing.
Procedure for checking and setting the spark electrode gap.
Procedure for accessing and removing the heat exchanger.
Details on flame sensing current and electrode location.
Instructions for checking, cleaning, and replacing filters.
Information on lubrication requirements for motors and wheels.
Procedure for inspecting the supply air blower wheel.
Instructions for inspecting and cleaning the evaporator coil.
Instructions for cleaning and inspecting the condenser coil.
Checks for wiring, voltage, and amp-draw on unit components.
Details on hybrid and standard roof curb options.
Details on supply/return transitions and outdoor air dampers.
Details optional flush mount and extended mount diffusers.
Details on economizer modes: TMP, ODE, DIF, GLO.
Description of gravity exhaust dampers for downflow/horizontal applications.
Details on power exhaust fans for downflow applications.
Details of electric heater kit for cold weather operation.
Description of factory and field installed smoke detectors.
Description of the blower proving switch.
Description of the dirty filter switch.
Details on kits for converting to LP or propane fuel.
Description of the CO2 sensor for IAQ monitoring.
Information on Healthy Climate germicidal UVC lights.
Description of the overflow switch for cooling operation interruption.
Explains the dehumidifying mode of operation for hot gas reheat.
Description of reheat coil solenoid valves.
Details on setting and adjusting the reheat setpoint.
Information on the A91 humidity sensor output voltage.
Procedure for testing hot gas reheat operation.
Describes default operation conditions for reheat.
Information on additional cooling stages and reheat interaction.
Details reheat operation based on thermostat mode and humidity demands.
Using design specifications to set up the blower CFM.
Procedure to determine and set the maximum blower CFM.
Procedure for setting blower speeds using the mobile app.
Setting minimum damper positions for ventilation air.
Configuration for bypassing the supply air inverter.
Steps for starting up the VAV system and its components.
Table for recording adjusted setpoints for VAV system parameters.
Wiring diagram for the VAV pressure transducer.
Checking unit mechanical operation via mobile app.
Procedure for manually bypassing the VFD for constant air volume.
Wiring diagram for the gas heat sections of the unit.
Key to components and connections shown in the gas heat wiring diagram.
Step-by-step operation sequence for gas heat.
Details operation of the low ambient kit.
Wiring diagram showing thermostat connections to the unit controller.
Notes on thermostat hookup and programmable settings.
Wiring details for the economizer and its sensors.
Description of the different economizer operating modes.
Sequence of operation for the economizer in 156/180U units.
Step-by-step sequence for first stage cooling.
Step-by-step sequence for second stage cooling.
Sequence for blower operation with VFD bypass.
Sequence for blower operation without VFD bypass.
Sequence of operation for the economizer in 210-300U units.
Step-by-step sequence for first stage cooling in 210-300U units.
Step-by-step sequence for second stage cooling in 210-300U units.
Sequence for blower operation with bypass in 210-300U units.
Sequence for blower operation without bypass in 210-300U units.
