A wall-mounted split is the default UK house job: cheaper, easier filters, no ceiling void. A cassette sits in a suspended ceiling and throws air from the centre of a shop, office or wide living room. Choose cassette only if you have the void, the condensate route and a reason a wall unit cannot throw across the space.
Cassette or wall, not which brand
The cassette guide, the one-way cassette guide and the home ceiling cassette guide cover formats. This page is the decision: cassette or wall, not which cassette brand.
Wall units win most houses because there is no grid ceiling. Cassettes win shops, open offices and some new-build flats with a proper void. A four-way cassette in a 2.4 m plastered period room is the wrong product.
- Wall: cheaper, visible, easy filters, short install.
- Four-way cassette: commercial ceilings, even throw, needs void depth.
- One-way cassette: corridors and some living rooms with a shallow bulkhead.
- Neither hides the outdoor unit.
What the survey must catch
Void depth, joist direction, filter access, and a condensate route that does not drip on stock or a landing. A cassette with no access panel will not be maintained. Static pressure and throw matter in a long shop. A wall unit aimed at a door will freeze the entrance and leave the till warm.
The same void, drain and outdoor siting rules apply in Manchester as in London. Access and parking change. The product does not.
Cost shape
As a 2026 illustration, a domestic wall split still undercuts a domestic cassette because of first and second fix in the ceiling. Commercial cassettes can look cheaper per indoor than a row of walls once you need even coverage over a sales floor. Hedge any web from-price until someone has lifted a ceiling tile.
The cassette cost guide and the wall-mounted cost guide are the two budget pages. Do not average them.
How to brief it
Photos of the ceiling, a tape shot of void depth if you can, and whether customers walk under the unit. Say if you hate wall boxes. Say if there is no void, because then we are talking bulkhead or wall, not a cassette fantasy.
Use the quote form. Local installers who do shops weekly will not try to hang a four-way in a cottage.
Frequently asked questions
Can I put a cassette in a normal UK house?
Only with a ceiling void or a built bulkhead, plus condensate and access. Most houses should stay on a wall unit or a hidden ducted unit. The hidden air conditioning guide covers bulkheads.
Is a cassette quieter than a wall unit?
Sometimes in the occupied zone, because the fan is in the ceiling. It can still roar in a cheap grid. Compare sound data and ask about night mode. Outdoor noise is a separate problem.
Do I need four-way or one-way?
Four-way for a roughly square shop or office bay. One-way for a corridor or a room where you can only blow in one direction. The one-way cassette guide covers the narrow-room case.
Core buying guides
Start with these high-intent guides, then dig into the rest of the library.
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.