Split vs portable
air conditioning
A portable unit costs 300 pounds and a fitted split costs 1,750. That is the whole argument as most people meet it, and it leaves out the three numbers that actually decide it: noise, running cost, and how much of the cooling reaches the room.
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A fitted split system is roughly three to four times louder to live with in reverse: a portable is typically 50 to 65 dB(A) in the room, against 19 to 24 dB(A) for a split. A split also uses considerably less electricity for the same cooling, because a portable throws away part of its own output through the window hose.
There are still three situations where a portable is the right buy, and they are at the bottom of this page.
Side by side
| Portable | Fitted split | |
|---|---|---|
| Purchase price | £250 to £600 | £1,750 to £2,900 fitted |
| Noise, in the room | 50 to 65 dB(A). The compressor is indoors | 19 to 24 dB(A) indoors |
| Efficiency | Much lower. Warm air returns through the hose | High. Nothing is vented from the room |
| Cooling actually delivered | Reduced by the hose and the window seal | The rated output |
| Heating in winter | Rarely, and poorly | Yes, at 3 to 4 units of heat per unit of electricity |
| Window | Must stay part open around the hose | Closed |
| Floor space | Takes a corner of the room | None |
| Moving house | Comes with you | Stays, and adds to the property |
| Planning permission | None | None on a house meeting the conditions. Flats need it |
Every figure on this site is an estimate based on published UK market ranges and our own installation experience. It is not a quotation. The price you are given after the free survey is the price you pay.
Why a portable is louder than the number on the box
In a split system the compressor, which is the noisy part, is outside. In a portable it is in the room with you, eighteen inches from your foot. That is the entire difference and no amount of engineering closes it.
The practical consequence is not that a portable is annoying, it is that it is unusable in the two rooms people most want cooling in. You cannot sleep next to one comfortably and you cannot take a call over one.
The hose problem, which is where the efficiency goes
A single-hose portable takes air from the room, uses it to cool its condenser, and blows it out of the window. That air has to be replaced, and it is replaced by warm air pulled in from outside and from the rest of the house through every gap in the room, including the one around the hose.
So the unit is cooling the room and simultaneously importing warm air into it. A twin-hose model reduces this substantially and costs more; most sold in the UK are single-hose.
That is why a portable rated at 3.5kW does not cool a room like a 3.5kW split. Part of its output is spent undoing what its own hose is doing.
When a portable is genuinely the right answer
Renting, where you cannot fit anything and will not be there long enough to justify asking. A portable is the only option and it is better than no option.
Occasional use. If the honest answer is five or six really hot nights a year in one room, the payback on a fitted system is long and a portable is a reasonable purchase.
A room where nothing can be fitted. An internal room with no outside wall within reach, or a listed building where consent will not be given. We would rather tell you that than take a deposit for a survey that ends in no.
Outside those three, the fitted system wins on every measure that matters after the first day, and the gap widens every summer.
Other things people weigh up
Single split vs multi-split
If you want more than one room cooled, this is the decision that shapes the whole installation: several small outdoor units, or one bigger one serving all of them.
CompareAir conditioning vs air source heat pump
These are the same technology wearing two names, and the confusion costs people real money.
CompareWhat happens on a survey
An hour, nothing to sign, and a written fixed price afterwards. The fastest way to settle any of this properly.
Free surveyQuestions people ask
How much cheaper is a portable air conditioner to run?
It is not cheaper, it is more expensive. A portable uses more electricity to deliver less useful cooling, because a single-hose unit continuously pulls warm replacement air into the room it is trying to cool.
A fitted split running at part load in a bedroom is commonly 12 to 22 pence an hour. There is a calculator using your own tariff on the running costs page.
Can I sleep with a portable air conditioner running?
Some people can and most cannot. A portable in a bedroom is typically 50 to 65 dB(A), which is between a conversation and a busy road, and the compressor cycling on and off is more disruptive than the steady level.
A fitted unit at 19 to 24 dB(A) is below the background noise of most bedrooms. It is the single biggest practical difference between the two.
Do portable units need the window open?
Yes, enough to pass the exhaust hose, and the seal kits supplied are usually poor. That opening is both a security consideration and a continuous route for warm air back into the room.
A fitted system runs with everything closed, which is also why it works better in a room facing a noisy road.
Not sure which way to go?
Tell us the rooms and what you are trying to achieve. We will say which of these we would fit in your property and why, before anybody quotes anything.
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