LG LD 024 Rooftop Units Installation Guide

LG LD 024 Rooftop Units

Product Information

• Specifications
  • Model: LG/LD Series
  • Capacity Options: 2, 3, 4, 5, 6, 6.5, 7.5, 8.5, 10, 12.5, 13, 15, 17.5, 20, 25 Tons
  • Parts Arrangement: Evaporator Coil, Reheat Coil (Optional), TXV, Blower (Direct Drive), Condenser Fan, Economizer (Optional), Coil Guards (Optional), Condensate Drain, Combustion Air Inducer, Burners, Gas Valve, Unit Controller, Compressor

Product Usage Instructions

• Safety Precautions
  • It is crucial to adhere to the following safety precautions:
  • Keep the unit area clear of combustible materials and flammable vapours.
  • Avoid obstructing air flow to the unit to ensure proper ventilation.
  • Always follow lock-out/tag-out procedures before maintenance.
  • Avoid contact with moving parts and sharp edges.
• Installation and Maintenance
  • Installation and maintenance should only be performed by licensed HVAC professionals or equivalent service agencies to prevent property damage or personal injury.
• Handling and Operation
  • When handling the equipment, wear gloves and protective clothing to avoid injury from sharp sheet metal edges.
  • Always keep hands, clothing, tools, and other objects away from moving parts to prevent accidents.
• Gas Safety
  • If you detect a gas smell near the appliance, follow the gas supplier’s instructions immediately and do not attempt to operate the unit until it is deemed safe.

FAQs

• What should I do if I smell gas?
  • If you smell gas near the appliance, immediately evacuate the area and contact your gas supplier or emergency services.
  • Do not operate the unit until it has been inspected and deemed safe for use.
• Can I perform maintenance on the unit myself?
  • No, all maintenance and servicing should be carried out by qualified HVAC professionals or authorized service agencies to ensure the safety and proper functioning of the equipment.

Safety

1. Keep the unit area clear and free of combustible materials, gasoline and other flammable vapours and liquids.
2. Do not obstruct airflow to the unit. The unit must receive an unobstructed flow of combustion and ventilating air.

WARNING

• The danger of explosion and fire. Failure to follow safety warnings exactly could result in dangerous operation, serious injury, death or property damage.

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.

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.

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 the blower, remove the 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, jewellery, tools, etc., away from moving parts.

WARNING

• The danger of electrical shock, explosion and fire.
• Improper servicing could result in dangerous operation, serious injury, death or property damage.

FUTURE REFERENCE

READ ALL INSTRUCTIONS IN THIS MANUAL AND RETAIN FOR FUTURE REFERENCE

WARNING FIRE OR EXPLOSION HAZARD: Failure to follow safety warnings exactly could result in serious injury, death, or property damage. Do not store or use gasoline or other flammable vapors and liquids in the vicinity of this or any other appliance. Installation and service must be performed by a qualified installer, service agency or gas supplier.

WHAT TO DO IF YOU SMELL GAS:

• Do not try to light any appliance.
• Extinguish any open flames.
• Do not touch any electrical switch; do not use any phone in your building.
• Leave the building immediately
• Immediately call your gas supplier from a neighbour’s phone. Follow the gas supplier’s instructions.
• If you cannot reach your gas supplier, call the fire department.

Parts Arrangement

LG 036, 048, 060, 072, 074 Parts Arrangement

LD 024, 036, 048, 060 Parts Arrangement

LG 092, 102, 120, 150 Parts Arrangement

LD 078, 102, 120, 122, 150 Parts Arrangement

LG 156, 180, 210, 240, 300 Parts Arrangement

LD 180, 240 Parts Arrangement

CAUTION

• Label all wires before disconnection when servicing controls. Wiring errors can cause improper and dangerous operations. Verify proper operation after servicing.

WARNING

• Electric shock hazard. Can cause injury or death.
• Before attempting to perform any service or maintenance, turn the electrical power to the unit OFF at disconnect switch(es).
• The unit may have multiple power supplies.

WARNING

• Do not use this furnace if any part has been underwater.
• A flood-damaged furnace is extremely dangerous.
• Attempts to use the furnace can result in fire or explosion.
• A qualified service agency should be contacted to inspect the furnace and to replace all gas controls, control system parts, and electrical parts that have been wet or the furnace if deemed necessary.

WARNING

• The danger of explosion. Can cause injury or product or property damage.
• If overheating occurs or if the gas supply fails to shut off, shut off the manual gas valve to the appliance before shutting off the electrical supply.

Unit Operation

• FOR YOUR SAFETY READ BEFORE LIGHTING BEFORE LIGHTING smell all around the furnace area for gas.
• Be sure to smell next to the roof because some gas is heavier than air and will settle on the roof.
• The gas valve may be equipped with either a gas control lever or a gas control knob.
• Use only your hand to push the lever or turn the gas control knob.
• Never use tools. If the lever will not move or the knob will not push in or turn by hand, do not try to repair it.
• Call a qualified service technician. Force or attempted repair may result in a fire or explosion.
• The unit is equipped with an automatic spark ignition system.
• There is no pilot. In case of a safety shutdown, move the thermostat switch to OFF and return the thermostat switch to HEAT.
• For logic units and units with electronic temperature controls, shut off the main disconnect and then turn it on to reset the ignition control.

Placing Unit Into Operation

WARNING: Danger of explosion and fire. Can cause injury or product or property damage. You must follow these instructions exactly.

Gas Valve Operation

1. Set the thermostat to the lowest setting.
2. Turn off all electrical power to the appliance.
3. This appliance is equipped with an ignition device that automatically lights the burner. Do not try to light the burner by hand.
4. Open the heat section access panel.
5. Turn the gas valve switch to OFF. See Figures 1, 2 or 3.
6. Wait five (5) minutes to clear out any gas. If you then smell gas, STOP! Immediately call your gas supplier from a neighbor’s phone. Follow the gas supplier’s instructions. If you do not smell gas, go to the next step.
7. Turn the gas valve switch to ON. See Figures 1, 2 or 3.
8. Close or replace the heat section access panel.
9. Turn on all electrical power to the appliance.
10. Set the thermostat to the desired setting.
    • NOTE – When the unit is initially started, steps 1 through 9 may need to be repeated to purge air from the gas line.
11. The ignition sequence will start.
12. If the appliance does not light the first time (the gas line is not fully purged), it will attempt up to two more ignitions before locking out.
13. If a lockout occurs, repeat steps 1 through 10.
14. If the appliance will not operate, follow the instructions “Turning Off Gas to Appliance” and call your service technician or gas supplier.

Turning off the gas to Unit

1. If using an electromechanical thermostat, set it to the lowest setting.
2. Before performing any service, turn off all electrical power to the appliance.
3. Open or remove the heat section access panel.
4. Turn the gas valve switch to OFF.
5. Close or replace the heat section access panel.

WARNING: Danger of explosion. Can cause injury or death. Do not attempt to light manually. The unit has a direct spark ignition system.

Burner Flame

WARNING: Danger of explosion and fire. Can cause injury or product or property damage. Periodically inspect burner flame to ensure proper unit operation.

ULNOx Units

• The primary air is permanently set for normal operation.
• The flame will be blue with some clear yellow streaking at the end of the flame.
• Inspect the burner flame periodically during the heating season using the inspection port provided on the burner access panel.

ULNOx Units

• ULNOx units are not equipped with gas orifices that supply each burner.
• Instead, a single gas orifice supplies gas to the air/gas elbow.
• An intake air orifice supplies combustion air to the air/gas elbow.
• The combustion air blower draws the air/gas mixture from the air/gas elbow into the air/gas plenum box.
• When the spark ignites the gas, the ignition sensor proves the flame and combustion occurs in the burner premix plate.
• The burner box liner directs the flames into the burner tube sleeves. Refer to figure 4.

Flue Passage and Vent Inspection

• Annually, before the heating season, inspect the combustion air louvres, vent cap, heat exchanger, burners (non-ULNOx units only), and combustion air inducer for corrosion, deterioration or deposits of debris.
• Remove any obstructions or blockage. On UNLOx units, periodically clean lint or other debris from the combustion air intake screen.
• See Figure 4, Figure 5, Figure 6, or Figure 7.

Service

• To maintain efficiency and longevity, your equipment must be serviced yearly by a qualified service technician.
• Failure to provide proof of service can void the warranty.

CAUTION

• Label all wires before disconnection when servicing controls. Wiring errors can cause improper and dangerous operations. Verify proper operation after servicing.

Servicing Filter

• Units are equipped with filters as shown in Table 1.
• Filters should be checked monthly and replaced when necessary.
• Take note of airflow direction marking on the filter frame when reinstalling filters. See Figure 8.

NOTE

• Replace factory-installed filters within 30 days of initial unit start-up. Refer to local codes or appropriate jurisdiction for approved filters.

WARNING

• Units are shipped from the factory with temporary filters.
• Replace filters before the building is occupied.
• Damage to the unit could result if filters are not replaced with approved filters.
• Refer to appropriate codes.

TABLE 1 UNIT FILTERS

• NOTE – Filters must be ULC-approved or equivalent for use in Canada.

Lubrication

• All motors are lubricated at the factory. No further lubrication is required.

156-300 Units –

• Blower shaft bearings are pre-lubricated. For extended bearing life, relubricate at least once every two years with a lithium base grease, such as Alvania 3 (Shell Oil), Chevron BRB2 (Standard Oil) or Regal AFB2 (Texas Oil).
• Use a hand grease gun for relubrication. Add only enough grease to purge through the bearings so that a bead of grease appears at the seal lip contacts.

Manifold Pressures – Non-ULNOx Units

• Manifold pressures are shown in Table 2. Refer to Figure 1 or 2 to locate pressure ports.

TABLE 2 MANIFOLD PRESSURES in.w.g

1st Stg

± 0.2

| 2nd Stg

± 0.3

| 1st Stg

± 0.2

| 2nd Stg

± 0.3

024, 036, 048, 060,

072, 074 Dual Heat

| 2.0

(0.47)

| 3.5

(0.87)

| 5.9

(1.47)

| 10.5

(2.61)

078-300| 1.6

(0.40)

| 3.7

(0.92)

| 5.5

(1.47)

| 10.5

(2.61)

Burners – Non-ULNOx Units
Clean the burners as follows:

1. Turn off the electrical power and the gas supply to the unit.
2. Remove the burner compartment access panel.
3. Remove top burner box panel. See Figure 9 or Figure 10.
4. Remove screws securing burners to burner support and lift the entire burner assembly from the orifices. Clean as necessary. The Spark gap on the ignition electrode must be properly set. Refer to the Heating Adjustment section in the installation instructions.
5. Replace burners and screws securing burner. Replace the top burner box panel.
6. Turn on the electrical power and the gas supply to the unit. Follow the operating instructions attached to the unit and use the inspection port in the access panel to check the flame.

Combustion Air Inducer

• A combustion air inducer proving switch checks the combustion air inducer operation before allowing power to the gas controller.
• The gas controller will not operate if the inducer is obstructed.
• Under normal operating conditions, the combustion air inducer wheel should be checked and cleaned before the heating season.
• However, it should be examined periodically during the heating season to establish an ideal cleaning schedule.

Clean the combustion air inducer as follows:

1. Turn off the electrical power and the gas supply to the unit.
2. On 078-150 units, remove the mullion on the right side of the heat section. On 156-300 units, remove the tube bracket support on the right side of the heat section.
3. Disconnect the pressure switch air tubing from the combustion air inducer port.
4. Remove and retain the screws securing the combustion air inducer to the flue box.
5. Clean the inducer wheel blades with a small brush and wipe off any dust from the housing. Clean accumulated dust from the front of the flue box cover.
6. Return the combustion air inducer motor and the vent connector to their original location. Secure with retained screws. It is recommended that the combustion air inducer gasket be replaced during reassembly.
7. On 078-150 units, replace the mullion. On 156-300 units, replace the tube bracket support.
8. Use a small brush to clean the combustion air inlet louvers on the heat access panel.

Flue Passageway and Flue Box

1. Remove the combustion air inducer assembly as described in the Combustion Air Inducer subsection.
2. Remove the flue box cover. Clean the flue box with a wire brush as required.
3. Clean the tubes with a wire brush.
4. Reassemble the unit. The flue box cover gasket and combustion air inducer gasket should also be replaced during reassembly.

Service Reminder

Call a qualified service technician if the unit is inoperative. Before calling, always check the following to be sure service is required:

1. Be sure electrical disconnect switches are ON.
2. Check the room thermostat for proper setting.
3. Replace any blown fuses or reset circuit breakers.
4. The gas valve should be ON.
5. Air filters should not be plugged in, limiting airflow.
6. Make sure all access panels are in place.

Repair Parts Listing

When ordering repair parts, include the complete model number and serial number listed on the ETL/CSA rating plate – e.g. LGM120U4EH1Y.

• Gas Heat Section Parts
  • Heat Exchanger
  • Combustion Air Assembly
  • Combustion Air Proving Switch
  • Burner Assembly
  • Burner Manifold Assembly
  • Main Burner Orifices
  • Flame Roll-out Switches
  • Auxiliary Limit Controls
  • Ignition Electrode Assembly
  • Ignition Lead
  • Ignition Sensor Assembly
  • Sensor Lead
  • Combination Gas Valve
  • Limit Controls
  • Ignition Controller
• ULNOx Units
  • Intake Air Screen
  • Intake Air Orifice
  • Air/Gas Elbow
  • Air/Gas Plenum Box
  • Burner Premix Plate
  • Burner Box Liner and Tubes
  • Inlet Reducer
  • Rubber Coupling
• Cooling Parts
  • Compressors
  • Condenser Fan Motors
  • Condenser Fan Blades
  • Condenser Fan Run Capacitors*
  • *Used only with PSC motor applications
  • Condenser Fan Mounting Bracket
  • Fan Grille
  • Indoor Blower Motors
  • Blower Wheel
  • Expansion Valve
  • Distributor
  • Exhaust Fans (Opt.)
  • Reversing Valve (LD and reheat units only)
• Electrical Control Parts
  • Unit Controller
  • Compressor Contactors
  • Circuit Breakers (Opt.)
  • Transformer (Control)
  • Transformer (Contactor)
  • Blower Contactor
  • Limit, Blower Relay
  • Heat Relays
  • Condenser Fan Relays
  • Capacitor CAB
  • Relay CAB
  • Disconnect Switch (Opt.)
  • Defrost Control (LD only)
  • Fan Control Board (LD only)

See unit nameplate for manufacturer and address.

• ©2022
• 508109-02
• 8/2022
• Supersedes 508109-01

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