Air conditioning installation
Air conditioning installation for homes in Kent and south-east London
We fit heat-and-cool air conditioning for bedrooms, lofts, home offices and whole houses across Dartford, Kent and south-east London. Olly surveys the rooms, sizes each unit by calculation and fits it neatly, usually in a day for one room.
How it works
What gets fitted: home air conditioning explained
Almost every home system we fit is a split system. It has two parts joined by a short run of pipes, and it heats as well as cools.
The indoor unit goes high on a wall, low on a wall or in the ceiling. It blows warm or cool air into the room and has a filter you can wash.
The outdoor unit sits on the ground or on a wall bracket. It holds the compressor and fan. In summer it takes heat out of your room and gets rid of it outside. In winter it runs in reverse and brings heat in from the outside air, even on a cold day. That is why these systems are also called air-to-air heat pumps.
Between them run two insulated copper refrigerant pipes, a power and control cable, and a small drain for the water the unit takes out of the air. They pass through one neat hole in the wall.
New split systems mostly use R32 refrigerant. Since 1 January 2025, new single splits holding under 3kg of the older, higher-impact gases such as R410A can no longer be sold in Great Britain (GOV.UK).
Air conditioning without an outdoor unit (a through-the-wall unit) does exist, but it is noisier and less efficient. It is a last resort, for example where a freeholder refuses an outdoor unit.
Where people fit it
Air conditioning for the rooms we fit most
Most of our installs are for homes, from a single bedroom to every room in the house.
Bedrooms
A small, quiet wall unit cools a bedroom in minutes and heats it on cold mornings. In Bexley we fitted a 2.5kW bedroom unit.
Bedroom air conditioningLiving rooms and kitchen-diners
Open-plan spaces with lots of glass may need a larger unit, or two indoor units so the air reaches every corner.
Wall-mounted unitsLoft conversions
Lofts get hottest of all, and sloping ceilings make the pipe route tricky. We have fitted lofts other firms turned down.
Loft conversion air conHome offices and garden rooms
Often the first room people cool. The same unit heats it in winter, in place of a plug-in heater.
Garden office air conFlats
Your lease may need the freeholder to agree first. We give you the details they usually ask for.
Air conditioning in a flatThe whole house
A multi-split runs several rooms from one outdoor unit. Ducted systems hide everything but slim grilles.
Ducted air conditioning
The free survey
What size air con do I need? We calculate it
The most common problem we see is the wrong size of unit in the wrong place. So every job starts with a proper look at the room.
- Heat gain and loss, room by room. Orientation, windows, insulation and how you use the room decide the size. Building regulations guidance (Approved Document L) says cooling should be sized from a heat-gain calculation and be no more than 120% of what the room needs.
- Rated in kW. 1kW is about 3,400 BTU an hour. Most single rooms need between 2kW and 5kW.
- The right spot for each unit. Inside, where the air reaches the whole room without blowing on the bed. Outside, away from windows.
- A noise check before we fit. We check the outdoor unit against the MCS 020(a) limit of 37 dB(A) at your neighbour's nearest door or window.
- A fixed written quote. The model, the size, where the pipes go and what is included. One customer put it simply: "Price we were quoted was the price we paid".
Choosing a system
Split system, multi-split or ducted: which do you need?
Most homes suit wall-mounted split units. The choice is mainly about how many rooms, and how much you want to see.
Single split: one room, one outdoor unit
One indoor unit on its own outdoor unit. It is simple, each room works on its own, and if one ever has a fault the others carry on. It is the usual choice for one or two rooms, or where the outdoor units can sit on different walls.
Multi-split: several rooms, one outdoor unit
Two to five indoor units run from one outdoor unit, so there is less on the outside wall. It suits a terrace or semi with limited wall space. One Bexleyheath home has seven indoor units on two multi-split systems. If you might add rooms later, we plan the outdoor unit for that.
Wall-mounted
The most popular choice. Slim units from plain white to design-led finishes.
Wall-mounted systemsFloor-mounted
Sits low on the wall, often where a radiator was. Good for lofts with sloping ceilings.
Floor-mounted systemsDucted
Hidden in the ceiling or loft, with only slim grilles in each room. Airzone zoning adds room-by-room control.
Ducted systemsCeiling cassette
Sits flush in a ceiling. Suits big open-plan rooms and businesses.
Ceiling cassettesChoosing between makes? Compare Daikin, Mitsubishi Electric and Panasonic. Replacing an old system? Read repair or replace first. Want each room on its own thermostat with a ducted system? See Airzone zoning.
A photo is often enough for a first idea of what will work.
On the day
What happens during air conditioning installation
One room is usually a one-day job. This is the order we work in.
Protect the room
Dust sheets and shoe covers go on. We move what needs moving and catch the dust as we drill.
Fit inside and out
Indoor unit on its bracket, a neat core hole behind it, outdoor unit on the ground or a wall bracket with anti-vibration mounts.
Pipe, test and fill
We pressure-test the pipework with nitrogen and pull a deep vacuum before releasing the refrigerant, the way manufacturers specify.
Commission and hand over
We test heating and cooling, set up the app, show you the remote and help you register the warranty.
Electrics: every system needs a suitable power supply and an isolator switch by the outdoor unit. We look at your consumer unit at the survey, and the quote says exactly what electrical work is included, so there are no surprises on the day.
Planning and permission
Do I need planning permission for air conditioning?
Usually not, for a house in England. We check your address before you commit to anything.
Since 29 May 2025, a unit that heats as well as cools (an air-to-air heat pump) on a house is normally permitted development. The outdoor unit has to meet size and siting rules and pass the MCS 020(a) noise calculation: 37 dB(A) at 1m from a neighbour's nearest door or window to a habitable room. We do that calculation as part of the survey.
Some homes need more care:
- Cooling-only units are not covered, which is one reason we fit heat-and-cool systems.
- Conservation areas: the outdoor unit cannot go on a wall or roof facing the road without planning permission.
- Listed buildings need consent.
- Flats have stricter limits, and the lease usually needs the freeholder's consent. See air conditioning in a flat.
Source: the planning rules for air source heat pumps (GPDO 2015, Schedule 2, Part 14, Class G, as amended in 2025). Our planning permission guide explains it in full.
Cost
How much does air conditioning installation cost?
Every quote we give is fixed and in writing, after a free survey. These are the things that move the price.
For a feel of the market, Which? (July 2026) put an air-to-air system for one room at about £1,900, and a multi-unit system for a three-bedroom semi at about £3,700. Selectra (October 2026) says prices in London and the South East run 20 to 30% above the national figures.
Is it cheaper to fit in winter? The kit costs about the same, but dates are far easier to get between October and April than in a heatwave. Read our air conditioning cost guide and what it costs to run. Asking about the new heat pump grant? Our air-to-air heat pump page explains the conditions.
- The size of each unit, from the heat-gain calculation.
- How many rooms, and whether a single split or a multi-split suits them.
- The brand and model. Design units such as Daikin Emura or Mitsubishi Electric Zen cost more than plain white ones.
- The pipe run and access. An outdoor unit straight behind the indoor unit is simplest. Long runs, or a unit high on a wall, take longer.
- Electrics and drainage. A new supply, or a condensate pump where gravity will not work.
Our installs
Neat inside and out
Real photos from our own air con installations across Kent and London.
Reviews
“Other companies had told me it couldn't be done”
Couldn't have asked for better service. The install was difficult and challenging due to access issues in loft. Olly made it look easy and dealt with everything in a professional and reassuring way. He went above and beyond as other companies had told me it couldn't be done. First rate job and top bloke.
The installation of 2 air-conditioning units (1 in the lounge and 1 in the bedroom) was seamless from olly coming to my flat to the compleatd installation. Olly was very professional in listening to my requirements and giving advice. On the day of installation Olly and Andy carried out the work in a professional, timely and clean manner. I would 100% recommend them to friends and family.
From initial contact to completion of install and subsequent aftercare, my experience with Apex was top class. The install itself was done in half a day and the room was left clean and tidy - you’d not know engineers had worked there! Not often I recommend someone, but I’ve passed their details on to friends who have used them and all had the same personal and great experience.
Had three units installed now and cannot fault either the equipment or Apex, from the initial unbiased advice, through to installation, I have no complaints whatsoever. Would recommend to anyone
Questions
Air conditioning installation FAQs
What size air conditioning unit do I need?
It depends on the room, not just its floor area: which way it faces, how much glass it has, the insulation, how many people use it and what heat the equipment gives off. We work it out room by room at the survey. A unit that is too big switches on and off and wastes energy. One that is too small runs flat out and never quite gets there.
How long does air con installation take?
A single room is usually fitted in a day, often less. One Lewisham customer wrote that "The install itself was done in half a day". A multi-split for several rooms or a ducted system takes longer, and the dates are in your quote. We put dust sheets down and clean up before we leave.
What happens to the water it makes?
When it cools, the indoor unit takes moisture out of the air. That water runs away through a small drain pipe, normally outside by gravity, often to a gully or down pipe. Where gravity will not work, for example on an inside wall, we fit a small, quiet condensate pump hidden in the trunking or the unit.
Can I install air conditioning myself?
Not a normal split system. Connecting the refrigerant pipes is F-gas work, and the law says it must be done by a company certified to do it. Certification also matters for the warranty, because manufacturers expect a qualified installer. Apex is an F-gas certified company on the REFCOM register. Portable units are the only true plug-in option, and they cool far less.
Is new air conditioning covered by a warranty?
Yes. Every new system comes with the manufacturer's warranty, and we help you register it. Manufacturers expect a yearly service to keep the warranty valid, and they can ask to see the records. Ask us which warranty applies to the brand and model in your quote. Our annual servicing keeps the records for you.
Get a free installation quote
Talk to Olly directly. He quotes and fits the jobs himself.
Quickest way to a price: send on WhatsApp
- A photo of the room and the outside wall
- Your town and what you need
- For a repair, the unit's label and any error code
Free survey and a fixed written quote for new systems. No obligation.