Air conditioning survey and unit sizing in London
A proper air conditioning survey for homes and offices across London: we measure the room, size the unit and agree the pipe route before any work starts.
Air conditioningGet the unit size right before anything is fitted
An air conditioning survey is where a good installation starts. One of our engineers visits your home or office, measures the room and works out how much cooling it really needs, so the unit we recommend is neither too weak to keep up nor so large that it switches on and off all day.
We also walk the route the pipework will take, choose the spot for the outdoor unit and check where the condensate can drain. You get a clear recommendation covering the indoor unit, the outdoor condenser, the pipework and the electrical supply. This is the first of six stages, and the indoor unit installation comes next.
What the survey covers
Every point below is checked in person, not estimated from a floor plan.
Room size and height
Floor area, ceiling height and volume, measured with a laser distance meter.
Heat load
Sunny windows, top-floor roofs, people and equipment all add heat to a room.
Unit capacity
We match the room to a 2.5, 3.5 or 5 kW split unit, or a multi-split for several rooms.
Outdoor unit position
A spot with clear airflow, safe access and low noise for your neighbours.
Pipe route and drain
The shortest tidy route between the units, and a fall or pump for the condensate.
Electrical supply
A spare way in your consumer unit, the cable route and the isolator position.
How the visit runs
Book a survey
Call or book online. We arrange a visit between 8am and 10pm, Monday to Saturday, and 8am to 6pm on Sunday.
We measure and check
The engineer measures each room, checks the walls and outdoor space and notes the pipe route.
You get a clear recommendation
The unit size, the work included and how it is charged, explained before you decide.
How air conditioning is sized
Cooling capacity is quoted in kilowatts, or in BTU per hour (1 kW is about 3,412 BTU/h). As a rough guide, a bedroom of 12 to 16 m² is usually served by a 2.5 kW (9,000 BTU) unit, and a living room of 25 to 30 m² by 3.5 to 5 kW. Those figures rise quickly with large south-facing windows, a top-floor flat under a flat roof, a kitchen opening onto the room, or an office full of people and computers.
Getting the size wrong costs you either way. An undersized unit runs flat out and never reaches the temperature you set. An oversized one cools the air quickly, then stops before it has removed enough moisture, so the room feels clammy and the compressor starts and stops far more often than it should.
Flats and listed buildings need extra checks. If you lease your home you may need consent from the freeholder before an outdoor unit goes on the wall, and conservation areas or listed buildings can have rules about the outside of the property. We flag these at the survey so nothing holds up the installation.
Frequently asked questions
How long does an air conditioning survey take?
A single-room survey is quick. Larger homes and offices take longer, because every room is measured and checked separately.
Do I need a survey for one room?
Yes. Even for one room, the size of the unit, the pipe route and the position of the outdoor unit decide whether the system works well and looks tidy.
Can you survey a flat or leasehold property?
Yes. We check the outdoor unit position, pipe route and noise, and tell you what to ask your freeholder or management company before the installation is booked.
How is air conditioning work charged?
Labour is charged at our published rates by time band, which you can check on the pricing page before you book. After the survey we explain what the unit and materials will add, so there are no surprises.
Book your air conditioning survey
Know the price before we start
Every service on this site has a published rate by time band. Check what your job costs, then book the slot that suits you. You can also return to the air conditioning overview or browse all our services.
Published rates
Air conditioning hourly rates in London
You pay a first-hour rate, then a lower rate for each extra half hour. The rate depends on the day and time of the visit.
| Air conditioning | Mon–Fri 8am–6pm | Mon–Fri 6pm–10pm | Saturday 8am–6pm | Sunday 8am–6pm |
|---|---|---|---|---|
| First hour | £85 | £88 | £88 | £98 |
| Each extra half hour | £42 | £45 | £50 | £52 |
| Daily rate | £495 | — | — | — |
Rates apply to jobs inside the M25. Minimum charges apply. Materials are charged in addition to labour, and shopping time for materials is charged at £35 per hour. See the full rate card.
Why Plumbery
Qualified, insured and upfront about price
Every engineer we send is registered or qualified for the trade they work in, and you can check the details before anyone starts.
- Gas Safe registeredGas and heating work is done by Gas Safe registered engineers.
- NICEIC qualifiedElectrical work is done by NICEIC-qualified electricians.
- F-Gas certifiedAir conditioning work is done by F-Gas certified engineers.
- Fully insuredEvery job is covered by our insurance.
- Rates published in advanceOur hourly rates are on the pricing page. Nothing starts until you agree the rate.
- Paperwork includedGas safety certificates and electrical records are provided on completion.
- Registered companyPlumbery Ltd, company no. 11677583, registered in England and Wales.
All air conditioning services
Electrical connection
Commissioning and handover