Panasonic Etherea and Mitsubishi Electric MSZ-AY are both mainstream UK wall splits in the sizes houses actually buy. Etherea's headline extra is nanoe X air treatment. AY's is very low indoor fan noise and a deep bedroom install base. Pick after a survey has fixed the same nominal cooling kW and a legal outdoor position. Filtration features are not a medical treatment. Both need an F-gas install.
nanoe X on one fascia, a very low fan on the other
Etherea is Panasonic's main residential wall indoor, and current UK models are sold around nanoe X. AY is the quiet M Series workhorse above HR and below the designer LN. Apps differ: Panasonic Comfort Cloud on current Etherea setups, MELCloud on Mitsubishi. Confirm the interface is included on the code you are buying.
For sleep, compare indoor sound at the lowest fan speed on the exact sizes. AY is specified so often because that number is genuinely low on current models. Etherea can still be right for a bedroom if its sheet is acceptable and you want the air-treatment feature. For a living room that runs all afternoon, either can work once the kW matches the glass. Energy Saving Trust describes these as air-to-air heat pumps when heating is part of the job.
Keep nanoe X off the medical shelf
Keep nanoe X in proportion. It is a real product difference. It is not a cure for asthma, hay fever or a damp house. Clean the filters. If symptoms are the reason you are buying, talk to a clinician as well as an installer.
As a 2026 illustration, installed single splits in this class still overlap in the high hundreds to a few thousand pounds including VAT on a straightforward house. Panasonic equipment often prices a little under an equivalent Mitsubishi, which is how Etherea wins tenders. Labour and access can wipe that out.
Boards, warranties and a condenser under a window
Mitsubishi's domestic network is broader. Panasonic-competent firms are common enough that a good local one is not a gamble. Ask who registers the warranty and how long a board takes. Same kW first. Then lowest-fan sound, whether nanoe X matters to you, the app, and the firm who will return.
GOV.UK F-gas certification is what the company doing the refrigerant work needs. If one survey said Etherea and another said AY, send both model codes so the duty can be checked rather than the slogans.
Frequently asked questions
Is nanoe X a reason to pick Etherea over AY?
It is a reason if air treatment is something you want and the survey already matches on kW and siting. It is not a reason to accept a worse outdoor position, and it is not a medical device.
Which is quieter at night?
AY is the indoor most UK bedroom quotes use when fan noise is the priority. Still compare the figures for your size, and remember the outdoor unit. A quiet fascia cannot hide a condenser on a bracket outside the window.
Do I need F-gas certification if the unit is only for a bedroom?
The company doing the refrigerant work does. Room use does not change that.
Will the filter brand fix a condenser under a neighbour's bedroom?
No. If the only outdoor wall is under a neighbour's bedroom, change the wall or pause. Neither indoor is a strategy for a bad condenser location.
Can Etherea join a Mitsubishi multi outdoor I already own?
No. If you already own a Mitsubishi multi outdoor, Etherea will not join it. Do not mix Panasonic indoors with Mitsubishi outdoors.
Core buying guides
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Related guides
Sources and further reading
How this guide was prepared
This guide was written by the Local AC Installers Editorial Team. We compare official guidance, legislation and established consumer information, separate general information from project-specific advice, and show publication dates and sources. We do not accept installer accreditation claims at face value.