The choice between a single split, a multi-split and a ducted system is really a choice about how many rooms you want to cool, how much building work you are willing to accept, and how visible you are prepared for the equipment to be. Get that order right and the technical decision follows easily. Get it wrong and you either pay for capacity you never use, or spend three years adding units piecemeal to a house that should have been planned once.
Key takeaways
- One or two rooms, minimal disruption: single splits.
- Three to five rooms with one outdoor unit and one elevation to keep tidy: multi-split.
- Whole house, invisible grilles, renovation already happening: ducted.
- Every additional outdoor unit is another elevation compromise — plan the full picture up front.
- All three types provide efficient heating as well as cooling.
Single split: one indoor unit, one outdoor unit
The single split is the workhorse of UK domestic cooling: one wall-mounted indoor unit connected by a pair of insulated copper pipes to one outdoor condenser. It is the cheapest way to make one room comfortable, the quickest to install, and the easiest to service.
- Best for: a principal bedroom, a home office, a loft conversion, a nursery, a single hot room.
- Typical installed cost: £1,800 – £3,200.
- Install time: usually one day.
- Disruption: one core hole, some trunking, an electrical connection. No structural work.
The limitation is scale. Each single split needs its own outdoor unit, so three rooms means three condensers, three sets of pipework and three positions on the elevation. Two is usually the sensible ceiling before a multi-split becomes the better answer.
Multi-split: several rooms, one outdoor unit
A multi-split connects two to five indoor units to a single larger outdoor unit. Each room keeps its own controller and setpoint, and rooms that are unoccupied simply do not call for cooling.
- Best for: an entire first floor, or the two or three rooms a family actually uses in hot weather.
- Typical installed cost: £4,500 – £9,000 depending on unit count and pipe routing.
- Install time: two to three days.
- Disruption: more pipework to route and conceal, often through a loft or riser.
The two advantages that matter most are visual and practical. Visually, one condenser instead of four keeps the elevation clean — which is often the deciding factor in conservation areas around Ripley and the surrounding villages. Practically, one outdoor unit means one service visit, one set of filters to worry about at the condenser end, and one point of electrical supply.
The trade-off is shared capacity. If every room calls for full cooling simultaneously on the hottest afternoon of the year, a multi-split will typically deliver slightly less per room than dedicated singles would. In real households, that scenario is rare enough not to matter — but it does mean the outdoor unit must be sized by someone who has thought about your actual usage rather than just adding the indoor units together.
Ducted: cooling you cannot see
A ducted system hides a fan coil unit in a loft, ceiling void or bulkhead and delivers conditioned air to each room through insulated ductwork and discreet slot or circular grilles. Nothing is visible in the room but the grille and a wall controller.
- Best for: full renovations, new builds, high-specification interiors, and properties where wall-mounted units are unacceptable visually.
- Typical installed cost: £4,000 – £7,000 per zone, so a whole house is commonly £10,000 – £25,000.
- Install time: weeks, sequenced with other trades.
- Disruption: substantial. Ceiling voids, bulkheads, plastering and decoration are all involved.
Ducted systems are superb when they are designed in from the start and disappointing when they are forced into a finished house. The critical constraint is void depth: you need somewhere for the fan coil and the duct runs to live. Bungalows and properties with generous lofts are the easiest retrofits; two-storey houses with shallow floor zones are the hardest.
Side by side
| Single split | Multi-split | Ducted | |
|---|---|---|---|
| Rooms served | 1 | 2 – 5 | Whole house |
| Outdoor units | 1 per room | 1 total | 1 – 2 total |
| Visible indoors | Wall unit | Wall unit per room | Grille only |
| Cost | £ | ££ | ££££ |
| Disruption | Low | Medium | High |
| Best moment to install | Any time | Any time | During renovation |
| Individual room control | Yes | Yes | By zone |
Room-by-room guidance
Bedrooms
Sound level is the specification that matters here, not capacity. Look for indoor units quoted below about 20 dB(A) on their lowest fan speed, and insist the unit is positioned so airflow is not blowing directly across the bed. A slightly larger unit running gently is quieter than a small one running hard.
Home offices and garden rooms
These are usually the strongest case for cooling in a UK home, because they combine glazing, equipment heat, and all-day occupancy. They also benefit most from the heating side in winter. A single split sized properly for the glazing will do the job.
Open-plan kitchen-diners
The hardest room in the house. Cooking heat, big glazed doors, and constant door opening mean the load is high and variable. Expect to need meaningful capacity, and consider whether a second smaller unit at the far end will outperform one large unit trying to throw air across ten metres.
Loft conversions
Loft rooms overheat because they sit under the hottest surface of the building and often have limited insulation depth in the roof slope. They are also frequently the furthest point from a sensible condenser location, so budget for a longer pipe run.
Retrofit vs planned install
If a renovation is anywhere on your horizon in the next two years, wait and design the cooling into it. Running pipework while floors are up and ceilings are open costs a fraction of doing it afterwards, and it opens up concealed and ducted options that are otherwise impractical.
If no building work is planned, do not force a ducted solution. A well-placed multi-split with tidy routing gives you 90% of the benefit for a third of the cost and a fraction of the mess.
Questions to ask at survey
Ask your installer
- What heat load calculation did you use for each room, and what glazing figures went into it?
- If I add a room in two years, does this design accommodate it?
- Where exactly will the pipework run, and how will it be concealed?
- What is the sound rating of the indoor unit at low fan speed?
- What is the sound rating of the outdoor unit at the proposed position?
- Will the system heat as well as cool, and what is its seasonal efficiency in heating mode?
A good survey produces answers to all six. If a quote arrives without any of them, it is a price rather than a design.
Frequently asked questions
Can I add rooms to a multi-split later?+
Only if the outdoor unit was specified with spare ports and capacity at the outset. Tell your installer about future plans at survey stage — it usually costs very little to allow for it then.
Are portable air conditioners a reasonable alternative?+
For occasional emergency use, yes. As a permanent solution they are noisy, inefficient, and require a window to be part-open for the exhaust hose, which lets warm air straight back in.
Do ducted systems cost more to run?+
They can, because you are conditioning more volume and there are duct losses. Well-designed zoning offsets much of that by only cooling the areas in use.
Which type is quietest indoors?+
Ducted, because the fan coil sits away from the room. Among visible options, a premium wall unit on low fan speed is very close.