Multi-splits for 3 rooms at 6 kW (21,000 BTU) in the UK: 18 models
LG MJ 6.2 kW (MU3R21U23) is the quietest of these 18 3-room multi-splits at ≈62.0 dB(A) outside. If one outdoor unit will serve 3 rooms, check the pass distance before the brand.
computed
Ranked models
18 models match this list. Multi-split with 3 indoor units, quietest outside first.
EPREL manufacturer-declared registrations · snapshot 25 Sep 2026 · n=18 · Multi-split with 3 indoor units, quietest outside first; noise via contract_engine MCS 020a Q=2, no barrier · updated 25 Sep 2026 · version 1.0.0 · CSV of the values on this page
How this page was calculated
If the calculated sound pressure level at all assessment positions is equal to or lower than 37.0 dB(A) then the heat pump will comply with the Permitted Development noise limit
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Better than a best-of roundup with no figures: every row is a registered number and a link to the model card.