
LG MU3R21.U21 Triple Zone Multi-Split Outdoor Unit
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Retail prices include VAT.
The LG MU3R21.U21 is a high-performance triple-zone multi-split outdoor unit designed to provide versatile climate control for up to three indoor units. With a robust 6.2kW (21,000 BTU) cooling capacity, this unit is the ideal choice for larger UK residences or small office suites where multiple rooms require independent temperature management. By connecting various indoor styles—such as wall-mounted units, ceiling cassettes, or floor consoles—to this single outdoor chassis, you save significant external wall space and simplify the installation process. The unit features LG's advanced R32 refrigerant, which offers a much lower global warming potential than older gases, aligning with modern environmental standards. Its smart inverter technology ensures that the compressor adjusts its speed based on demand, providing consistent comfort without the energy spikes associated with traditional systems. Built to withstand the British weather, the outdoor unit features a corrosion-resistant Black Fin coating on the heat exchanger, ensuring long-term durability and reliability. Whether you are looking to upgrade your home’s comfort or provide a professional environment for your staff, the MU3R21 offers the perfect balance of power, efficiency, and smart connectivity.
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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
Specifications
Description
The LG MU3R21.U21 is a high-performance triple-zone multi-split outdoor unit designed to provide versatile climate control for up to three indoor units. With a robust 6.2kW (21,000 BTU) cooling capacity, this unit is the ideal choice for larger UK residences or small office suites where multiple rooms require independent temperature management. By connecting various indoor styles—such as wall-mounted units, ceiling cassettes, or floor consoles—to this single outdoor chassis, you save significant external wall space and simplify the installation process. The unit features LG's advanced R32 refrigerant, which offers a much lower global warming potential than older gases, aligning with modern environmental standards. Its smart inverter technology ensures that the compressor adjusts its speed based on demand, providing consistent comfort without the energy spikes associated with traditional systems. Built to withstand the British weather, the outdoor unit features a corrosion-resistant Black Fin coating on the heat exchanger, ensuring long-term durability and reliability. Whether you are looking to upgrade your home’s comfort or provide a professional environment for your staff, the MU3R21 offers the perfect balance of power, efficiency, and smart connectivity.
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
£1424
This AC / season
£475
You save / season
£950
~67% less electricity
| Heating method | Electricity / season | Cost / season | Efficiency | Summer cooling |
|---|---|---|---|---|
| This heat-pump AC | 1758 kWh | £475 | Up to 300% | |
| Plug-in electric heater | 5275 kWh | £1424 | 100% | |
| Electric storage heater | 5275 kWh | £1424 | 100% |
Heat output estimated from this unit's 24,000 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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