Winter is coming — your air conditioner heats too. Cut heating bills by up to 67% vs electric heaters.

🇬🇧 Delivering air conditioning across the UK — free UK mainland delivery on in-stock units
LG MU3R21.U21 Triple Zone Multi-Split Outdoor Unit
LG

LG MU3R21.U21 Triple Zone Multi-Split Outdoor Unit

In StockEnergy A++
£1,465.000

Trade pricing available — apply or sign in for your trade rate

Dispatched in 3-5 working days
UK-Wide Delivery
Free UK mainland delivery on in-stock units

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.

1

Need it installed?

We'll match you with a local HVAC engineer.

Smart-home ready

Connects natively with the systems below — control by app or voice.

Amazon AlexaGoogle Home
  • Free UK mainland delivery on in-stock units
  • Manufacturer warranty included
  • 14-day returns

Specifications

Cooling Capacity21,000 BTU
Recommended Room SizeUp to 75m² total
Energy RatingA++
Smart HomeAmazon Alexa, Google Home
Noise Level
CategoryMulti-Split System AC
SKUMU3R21.U21

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 methodElectricity / seasonCost / seasonEfficiencySummer cooling
This heat-pump AC1758 kWh£475Up to 300%
Plug-in electric heater5275 kWh£1424100%
Electric storage heater5275 kWh£1424100%

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 →

You may also need

Sealey Window Sealing Kit for Air Conditioner Ducting
In Stock
Save £5.00
Sealey

Sealey Window Sealing Kit for Air Conditioner Ducting

0 N/A
Energy A
£24.99inc VAT
£29.99
Dispatched in 1-2 working days
Sealey Replacement Exhaust Hose for Portable Air Conditioners
In Stock
0
Sealey

Sealey Replacement Exhaust Hose for Portable Air Conditioners

0 N/A
Energy A
£35.50inc VAT
0Dispatched in 2-3 working days
Sealey Universal Remote Control for Air Conditioners
In Stock
0
Sealey

Sealey Universal Remote Control for Air Conditioners

0 N/A
Energy A
£19.95inc VAT
0Dispatched in 1-2 working days

Customer reviews

No reviews yet — be the first to share your experience.

Write a review

Reviews are moderated before publishing.