Multi F Engineering Manual

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Table Of Contents

Multi F MAX Heat Pump Condensing

Units

General

A Multi F MAX multi-zone system is comprised of one heat pump

outdoor unit connected up to eight indoor units through a branch

distribution unit (BD) using a single refrigerant piping circuit, and

includes integrated controls supplied by LG. Factory-designed and

supplied Y-branches may be used as well.

The outdoor unit is internally assembled, wired, and piped from the

factory; all LG components are manufactured in a facility registered

to ISO 9001 and ISO 14001, set by the International Organization for

Standardization (ISO). The LG Multi F MAX multi-zone heat pump

system components comply with Underwriters Laboratories (UL)

1995 Heating and Cooling Equipment Standard for Safety. The units

are certified to AHRI 210 / 240.

Temperature Ranges

The heat pump outdoor units are capable of operating in cooling

mode from 14°F to 118°F ambient dry bulb (installing an optional

Low Ambient Wind Baffle Kit will allow operation down to -4°F in

cooling mode for Multi F MAX systems). The heat pump outdoor

units are capable of operating in heating mode from -4°F to +64°F

ambient wet bulb without additional low ambient controls.

Frame

Multi F MAX condensing unit case is constructed from pre-coated

metal that has been tested in accordance with ASTM B-117 salt

spray procedure for a minimum of 1,000 hours. Case has a remov-

able front panel to allow access to major components and control

devices, and legs to secure the unit during installation.

Refrigerant System

Multi F MAX systems have a single refrigerant circuit field piped with

a manufacturer-supplied BD unit(s) and Y-branches (if applicable) to

multiple (ducted, non-ducted or mixed) indoor units to effectively and

efficiently control the heating or cooling operation of the multi zone

system. All refrigerant lines from the outdoor unit to the BD unit(s)

and from the BD unit(s) to indoor units are field-installed and must

be insulated separately.

Multi F MAX systems use R410A refrigerant. The LMU481HV and

LMU541HV outdoor units are equipped with a refrigerant strainer,

check valves, oil separator, hot gas bypass valve, accumulator,

four-way reversing valve, electronic expansion valve(s) (EEV), high

side and low side refrigerant charging ports, and a service port.

The outdoor unit also includes sensors for suction temperature,

discharge temperature, high-pressure, low-pressure, heat exchanger

temperature, and outdoor temperature conditions. The LMU601HV

outdoor unit includes the components cited above (except hot gas

bypass valve) in addition to a sub-cooled heat exchanger, vapor

injection and vapor bypass circuit.

Refrigeration Oil Control

The outdoor unit has an oil separator to separate oil mixed with the

refrigerant gas during compression and return oil to the compressor.

The outdoor unit also has an oil injection mechanism to ensure a

consistent film of oil on all moving compressor parts at low speed.

Compressor

Multi F MAX condensing units

are equipped with one hermeti-

cally sealed, digitally controlled,

inverter driven R1 scroll com-

pressor that includes Teflon™

coated bearings. The inverter

motor is capable of providing

a modulation range of 10Hz

to 130Hz for LMU481HV and

LMU541HV, or 10Hz to 130Hz

(cooling) and 10Hz to 150Hz

(heating) for LMU601HV, with

control in 1Hz increments. The

compressor uses a factory-

charge of Polyvinyl Ether (PVE)

oil, and is mounted to avoid the

transmission of vibration.

Fan and Motors

The Multi F MAX outdoor unit includes two direct drive variable

speed propeller fans with Brushless Digitally Controlled (BLDC)

motor with a horizontal air discharge.

Fan blades are statically and dynamically balanced propeller fans

made of durable Acrylonitrile Butadiene Styrene (ABS) plastic, and

include a raised fan guard to limit contact with moving parts. The

motors have inherent overload protection, permanently lubricated

bearings, and a maximum speed up to 670 rpm for LMU481HV and

LMU541HV, or 750 rpm for LMU601HV. Multi F MAX outdoor unit

has a horizontal discharge airflow.

Outdoor Unit Coil

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cally bonded on copper tubing. Coils have a minimum of two rows

for LMU481HV and LMU541HV, or three rows for LMU601HV, a

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terial with hydrophilic coating that has been tested in accordance with

ASTM B-117 salt spray test procedure for a minimum of 1,000 hours.

Electrical

Multi F MAX outdoor unit have 208/230V, 1 phase, 60Hz electrical

power capable of operating within ±10% of the rated voltage.

Controls

Factory installed microprocessor controls in the outdoor unit, BD

unit(s), and indoor units perform functions to efficiently operate

the multi-zone system. System wiring must be installed in a tree

configuration from outdoor unit to BD unit(s) to indoor units through

four conductor power/transmission cable. The system is capable of

performing continuous operation, even when power is turned off to

an individual indoor unit.

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MULTI F MAX OUTDOOR UNIT

Figure 18: Multi F MAX

LMU481HV and LMU541HV

Outdoor Units.

MULTI F MAX OUTDOOR UNIT | 31

Multi F MAX Outdoor Unit Data

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