LG MU3R21.U21 6.2kW Multi-Split Outdoor Unit
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The LG MU3R21.U21 is a versatile 6.2kW multi-split outdoor unit designed to power up to three indoor units. This system is ideal for medium-to-large residential spaces, offering the flexibility to maintain different temperatures in various rooms simultaneously. With its advanced dual inverter compressor, the unit provides exceptional energy efficiency and quiet operation, ensuring that your home remains comfortable without excessive noise or high energy bills. The unit is compatible with a wide range of indoor styles, allowing for a customisable climate control setup that fits your home's layout perfectly. Its robust construction and weather-resistant design make it a reliable choice for the UK climate. Whether you are cooling a living area or heating a bedroom, the MU3R21.U21 delivers consistent, high-performance results. With smart home compatibility, you can easily monitor and adjust your system settings from anywhere, providing ultimate convenience and control over your home environment.
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Smart-home ready
Connects natively with the systems below — control by app or voice.
- Free UK mainland delivery on in-stock units
- Manufacturer warranty included
- 14-day returns
Downloads & specs
More from LG →Manufacturer instructions
Installation of the LG MU3R21.U21 multi-split outdoor unit must be performed by a qualified, certified HVAC technician in compliance with local F-gas regulations. The unit requires a stable, level mounting surface with adequate clearance for airflow and maintenance. Refrigerant piping must be carefully routed, insulated, and connected to the indoor units using flare connections, followed by a mandatory vacuum pressure test to ensure system integrity. Electrical connections must follow the provided wiring diagrams, ensuring proper grounding and circuit protection. Once installed, the system requires a leak test and proper refrigerant charging based on the total pipe length. First power-on should only occur after verifying all connections and ensuring the system is free of moisture and contaminants. Always consult the specific technical manual provided with your unit for exact torque settings and electrical specifications.
Fixed units must be installed by a qualified F-gas engineer. Find an installer — we'll match you with a local HVAC professional.
Full Specifications
Description
The LG MU3R21.U21 is a versatile 6.2kW multi-split outdoor unit designed to power up to three indoor units. This system is ideal for medium-to-large residential spaces, offering the flexibility to maintain different temperatures in various rooms simultaneously. With its advanced dual inverter compressor, the unit provides exceptional energy efficiency and quiet operation, ensuring that your home remains comfortable without excessive noise or high energy bills. The unit is compatible with a wide range of indoor styles, allowing for a customisable climate control setup that fits your home's layout perfectly. Its robust construction and weather-resistant design make it a reliable choice for the UK climate. Whether you are cooling a living area or heating a bedroom, the MU3R21.U21 delivers consistent, high-performance results. With smart home compatibility, you can easily monitor and adjust your system settings from anywhere, providing ultimate convenience and control over your home environment.
Compare similar units
Side-by-side specs for other multi-split system ac in a similar BTU range.
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Stiebel Eltron
BroughtonReznor
Omega Altalfa
ClarkeBeldrayVYtronIXCostwaySuntec
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Senville
Comfee
AUX
Whynter
Viessmann
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Aermec
NIBE
Sinclair
Blyss
Fral
Whirlpool
Electrolux
Sharp
Cooper & Hunter
Daitsu
Dimplex
Bosch
Vaillant
Olimpia Splendid
Carrier
Toshiba
Mitsubishi Heavy Industries
DeLonghi
Hitachi
Pro Breeze
Meaco
AEGDevola
FujitsuelectriQSamsung
Woods
Midea
Haier
TCL
Hisense
LG
Gree
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Panasonic
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Mitsubishi ElectricAnnual energy savings estimate
How much this A++-rated unit could save versus a standard C-rated model, based on your usage.
This unit
170 kWh/yr
EER 13
Standard model
277 kWh/yr
EER 8
Est. saving
£28.76
107 kWh/yr less
Estimate based on the unit's energy-rating efficiency factor and cooling capacity (21,000 BTU). Actual savings vary with room size, climate and usage patterns.
Winter heating cost: this AC vs electric heaters
This unit reverses to heat your room in winter. Based on its 7 kW heat output used 5 hrs/day over a 150-day UK heating season at £0.27/kWh.
Electric heater / season
£1365
This AC / season
£455
You save / season
£910
~67% less electricity
| Heating method | Electricity / season | Cost / season | Efficiency | Summer cooling |
|---|---|---|---|---|
| This heat-pump AC | 1685 kWh | £455 | Up to 300% | |
| Plug-in electric heater | 5056 kWh | £1365 | 100% | |
| Electric storage heater | 5056 kWh | £1365 | 100% |
Heat output estimated from this unit's 23,000 BTU/hr rating. A heat pump moves heat (COP ≈ 3), so it uses about a third of the electricity of a direct-electric heater for the same warmth. Actual savings vary with room size, insulation, tariff and usage. See the full comparison →
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