For budgeting in July 2026, a domestic multi-split serving two rooms may commonly start around £3,000 to £5,500 including VAT, while three or four rooms can move into roughly £4,500 to £9,000 or more. London access, long pipe routes, concealed work, electrical upgrades and premium equipment can raise these figures. Multi-split pricing is highly site-specific, and separate single-splits may sometimes be cheaper or more resilient, so ask for both approaches where feasible.
Indicative multi-room budgets
A multi-split connects several indoor units to one outdoor unit. The July 2026 ranges above are broad consumer budgeting figures, not standard rates. Indoor-unit type, simultaneous capacity, refrigerant route and outdoor-unit position can change the result substantially.
A quote should list every indoor model and its room, the outdoor model, pipe lengths, controls and electrical requirements. A single unexplained system total makes it difficult to check whether competing proposals deliver the same capacity.
Benefits and trade-offs
One outdoor unit can reduce facade clutter and may help where outdoor space is limited. Each indoor unit normally provides room-level control, although the system's total available output and permitted operating combinations must be understood.
The shared outdoor unit is also a common point of failure. Pipework can be more complex than separate back-to-back splits, and future replacement may affect several rooms. Separate systems can offer redundancy and simpler routes but require more outdoor units.
- Compare one multi-split with separate single-split alternatives.
- Ask about simultaneous heating or cooling capacity, not just the sum of indoor nominal ratings.
- Check whether different rooms can demand heating and cooling at the same time.
- Confirm access for future leak testing, service and replacement.
Designing the pipe and drain routes
Every indoor unit needs refrigerant pipework, controls or communication wiring and a condensate route. Gravity drainage is desirable where possible. Pumps can solve difficult routes but add components that may require cleaning or replacement.
Concealed pipework should remain serviceable and be protected from damage. The proposal should identify trunking, penetrations, fire stopping where relevant and responsibility for decorative making good.
Permissions and professional installation
More rooms do not remove the need to consider planning, noise, lease restrictions and freeholder consent. Multiple indoor units connected to one condenser can still affect the external appearance and neighbouring amenity.
The refrigerant work should be completed by appropriately qualified personnel working through a certified company where the regulations require it. Request equipment schedules and commissioning documentation for future maintenance.
Frequently asked questions
Is a multi-split cheaper than separate split systems?
Sometimes, but not consistently. One outdoor unit may save space, while longer branch pipework and more complex labour may offset that saving. Compare equivalent written designs.
Can each room have a different temperature?
Indoor units generally have individual controls, but all rooms share the outdoor system's available capacity. Some systems cannot heat one room while cooling another.
What happens if the outdoor unit fails?
All connected rooms may lose heating or cooling until it is repaired. Separate single-splits provide greater redundancy.
Does one outdoor unit make planning permission unnecessary?
No. The development still needs to meet all applicable national rules, local constraints and property consents. Cooling-only use is particularly important when considering England's Class G heat-pump provision.
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.