Prices for air conditioning vary a lot, and the reasons are rarely the ones people assume. It is not usually the brand, and it is not usually the installer's hourly rate. It is pipe run length, condenser access, electrical work and how honestly the system was sized in the first place.
This guide sets out real London figures for 2026, breaks down what drives them, and shows you how to compare three quotes that look different on paper. It is written to be read before you start collecting prices, not after you have already picked one.
System prices at a glance
| System | Typically suits | Installed price |
|---|---|---|
| Single split — 2.5kW | Bedroom, home office, small study | £1,800 – £2,600 |
| Single split — 3.5kW | Living room, large bedroom, loft conversion | £2,200 – £3,000 |
| Single split — 5kW to 7kW | Open-plan kitchen-diner, large through-lounge | £2,800 – £3,800 |
| Multi-split — 2 rooms | Two indoor units, one outdoor condenser | £3,500 – £5,000 |
| Multi-split — 3 rooms | Typical London terrace or three-bed flat | £4,800 – £6,500 |
| Multi-split — 4 to 5 rooms | Whole-house cooling in a family home | £6,500 – £9,500 |
| Ducted / concealed | Period property or high-spec refurbishment, per zone | £4,000 – £6,000 |
The pattern to notice: the jump from one room to two is large, and every room after that is comparatively cheaper. That is because a multi-split shares one outdoor condenser and one set of external services across all the indoor units. If there is any chance you will want a second room cooled within a few years, it is substantially cheaper to specify the condenser for it now than to add a second outdoor unit later.
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Get a fixed priceThe costs that sit outside the headline price
These are the items that turn a competitive-looking quote into an expensive one after work has started. A good quote either includes them or tells you plainly that it does not.
| Item | When it applies | Typical cost |
|---|---|---|
| Scaffolding or access equipment | Where the condenser can't be reached safely from a ladder | £400 – £900 |
| Extra pipe run | Beyond the standard 3–5m included in most quotes, per metre | £30 – £60 |
| New electrical circuit | Dedicated supply from the consumer unit, including certification | £200 – £450 |
| Condenser mounting | Wall brackets, anti-vibration feet or a ground-level plinth | £150 – £300 |
| Making good and decorating | Filling and finishing core-drilled holes and chased runs | £100 – £300 |
| Annual service | Required to keep the manufacturer warranty valid, per year | £90 – £140 |
What actually drives the price up or down
Distance between the indoor unit and the condenser
This is the single biggest variable and the one homeowners rarely think about. Refrigerant pipework is expensive, and running it neatly through a finished house is slow work. A rear bedroom with the outdoor unit directly below is a straightforward job. The same unit in a front bedroom, with the condenser at the back of the house, can add a day of labour and a meaningful materials bill.
Where the outdoor unit can go
Ground level with clear access is best. Flat roofs, balconies, light wells and anything above the first floor may need scaffolding or a tower, which is a fixed cost regardless of how quick the actual installation is. In conservation areas the position may also be constrained by what is acceptable from the street — the Planning Portal's guidance on domestic air conditioning sets out the permitted development conditions, and a householder planning application where one is needed adds both a fee and several weeks.
Electrical work
Most systems need their own circuit run from the consumer unit. If your board is modern with a spare way and sits near the condenser position, this is a couple of hundred pounds. If it is a full board with no spare capacity, or a long way from where the unit needs to go, it costs more — and that difference is a common reason two quotes diverge.
Building fabric and finish
Core drilling a solid Victorian wall takes longer than a modern cavity. Concealing pipework inside a finished room costs more than running it in external trunking, and looks far better. Period London properties tend to sit at the higher end of every range on this page for exactly these reasons.
Equipment choice
Brand matters less than people expect — Daikin, Mitsubishi Electric, Panasonic, LG and Samsung all make good equipment, and published manufacturer specifications let you compare efficiency ratings and sound levels directly. What genuinely changes the price is capacity and indoor unit style: a slim ducted or concealed unit costs considerably more than a standard wall-mounted one doing the same job.
How to compare three quotes properly
If you get three prices back and they are hundreds of pounds apart, they are almost certainly not describing the same installation. Ask each installer for these five things in writing:
- The capacity of each indoor unit in kW, and the heat load calculation behind it. An undersized unit is cheaper to buy and will never keep the room comfortable.
- The pipe run length included, and the rate for anything beyond it.
- Whether electrical work is included or listed as provisional.
- Whether making good is included — that is, whether they fill and finish the holes they drill.
- Their F-Gas registration. Anyone handling refrigerant must be qualified; if that cannot be produced quickly, stop there.
Once all three quotes answer those questions, the comparison usually becomes obvious — and the cheapest one often stops being the cheapest.
Running costs and ongoing spend
A 3.5kW living-room unit draws roughly 1kW when working hard, which at current London electricity prices is somewhere around 25 to 35 pence an hour. Inverter systems then modulate down substantially once the room reaches temperature, so a full day of use rarely costs what a straight multiplication suggests. Across a typical British summer, most households find the seasonal running cost is a smaller number than they braced for.
The predictable ongoing cost is maintenance: an annual service at £90 to £140 per system. It is not optional in practice, because virtually every manufacturer makes it a condition of the five to seven year warranty.
Worth knowing: almost every system on this page heats as well as it cools, and does so efficiently. If lower heating bills rather than summer comfort is your real objective, read the air source heat pump cost and grants guide — that is where government funding applies, and it changes the arithmetic considerably.
Questions
Frequently asked questions
How much does it cost to install air conditioning in a London flat?
For one room, budget £1,800 to £2,600 for a 2.5kW split system supplied, fitted and commissioned. Flats carry two extra variables that houses often don't: where the outdoor condenser can legally and practically go, and whether the freeholder will consent to it. A balcony or flat-roof position that needs access equipment can add several hundred pounds, and freeholder consent can add weeks to the timeline even when it costs nothing.
Why are quotes for the same job so different?
Usually because they aren't the same job. Check three things on every quote: the capacity in kW of each indoor unit, the pipe run length included before extras kick in, and whether electrical work, commissioning and making good are inside the price or listed as provisional. A quote that omits any of those isn't cheaper — it's less complete, and the difference reappears as a variation once work has started.
Is air conditioning expensive to run in London?
Less than most people expect. A 3.5kW living-room unit typically draws around 1kW while cooling, which at current London electricity prices works out at roughly 25 to 35 pence an hour — and modern inverter units drop well below full draw once the room reaches temperature. Realistically, most households run their system hard for perhaps six to eight weeks a year, which keeps the annual cost modest.
Does air conditioning add value to a London property?
It's rarely a pound-for-pound return, but it is increasingly expected in higher-value London flats, top-floor conversions and new-build apartments where summer overheating is a known problem. A discreet, properly installed multi-split with concealed pipework reads as a specification upgrade; visible trunking running down a front elevation does the opposite. Installation quality matters more to value here than the brand on the unit.
Can I get a grant towards air conditioning?
Not for cooling. Government support is aimed at low-carbon heating, so the Boiler Upgrade Scheme covers air source heat pumps rather than air conditioning — even though the two technologies are closely related. If your main goal is to cut heating bills and carbon rather than to cool in summer, our heat pump cost and grants guide is the page you want.
How long does the whole process take?
From first call to a working system, usually two to four weeks. That's typically a few days to arrange the survey, a couple of days to prepare the quote, one to two weeks for equipment to arrive, and one to three days on site depending on how many rooms are involved. Freeholder consent or a planning application will extend that, which is why we identify those at survey stage rather than after ordering.