Hidden air conditioning in the UK usually means a ducted, bulkhead or concealed-ceiling indoor unit with only grilles on show. It costs more than a wall-mounted split and needs access panels, condensate planning and a survey. Hiding the unit is not the same as hiding the outdoor condenser or the pipe run.
What people mean by hidden
Hidden, concealed and no visible indoor box are the same job family: keep the fan coil out of sight. In UK houses that is usually a slim ducted unit in a bulkhead or loft, with a supply grille and a return. In offices it is a concealed ceiling unit or a true ducted system. A wall-mounted indoor unit with a painted pipe cover is not hidden. It is tidied.
The outdoor unit still needs air, access and a legal position. Hiding indoors does not shrink the condenser. If the garden cannot take a quiet outdoor unit, a beautiful bulkhead will not save the project. Cassettes sit in a suspended ceiling. They are discreet in offices and ugly in most period living rooms. Do not specify a cassette because it is hidden if you do not have a ceiling void. The concealed ceiling guide and the ducted air conditioning guide cover the two main formats.
- Grilles remain. Completely invisible indoors is a myth.
- Filter access must survive the plasterer.
- Outdoor siting is still the planning and noise problem.
What the survey must catch
Bulkhead depth, joist direction, loft hatch size, and a condensate route that does not drip on a landing. Filter access: if the only way to clean the coil is to demolish plasterboard, the system will not be maintained. Acoustic lining so the bulkhead does not become a drum.
2026 illustrations for hidden domestic systems sit above a comparable wall-mounted split because of first and second fix, grilles, and making good. Commercial concealed ceilings sit in a different budget again. Hedge any web price until the void has been measured. Planning and lease issues still attach to the outdoor unit, not the grille. Neighbours hear condensers, not supply slots.
Formats compared quickly
Wall-mounted: cheapest, visible, easy filters. Bulkhead ducted: hidden in one room or an open-plan, needs depth. Loft ducted: good for rooms below if fire and condensate are solved. Cassette: commercial ceilings. One-way cassettes: corridors and some living rooms with a flat ceiling void.
Open-plan kitchen-diners are the classic hidden brief because a wall unit fights the kitchen wall. Do not hide outdoor pipework inside a sealed box that traps heat. Decorative screens need open sides and a service gap. The outdoor unit position guide is the companion page.
Handover and living with it
Show the occupant where the filter is and how often to vacuum it. Leave a ceiling-access key if there is one. Record static pressure so the next engineer is not guessing.
If you later hate the draught, grilles can sometimes be rebalanced. Moving a ducted unit after plastering is a building project. Get the supply positions agreed on drawings, not on install day. Use the quote form if you want installers who do bulkheads rather than only wall splits.
Frequently asked questions
Can air conditioning be completely invisible?
Indoors, almost: grilles remain. The outdoor unit cannot be invisible if it is to reject heat. Screens and planting help. Sealed boxes do not.
Is hidden air conditioning more expensive?
Usually, yes. You pay for joinery or ceiling work, extra labour, and often a larger indoor unit. Running costs depend on the heat pump, not on whether you can see it.
Will a hidden system heat as well as cool?
If it is a reverse-cycle heat pump, yes, subject to fabric and outdoor siting. Hidden does not change the refrigeration cycle.
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.