Portable Air Conditioner Setup Guide

A portable air conditioner is the cheapest way to cool a single UK room without altering the building — typical units cost £250–£700 to buy, and a tradesperson will set one up properly for £80–£180 if you want help with venting, the window kit and the condensate drain. Most setups take 1–2 hours.

Portable AC is the right pick for renters, listed buildings, and rooms where a permanent split-system can't be fitted. It's noisier and less efficient than a fixed unit, but it requires no structural work and you can take it with you.

What a setup actually involves

"Plug in and switch on" works for the lucky few. Most homes need a bit more thought to get a unit running well:

• Venting the hot exhaust — every portable AC needs to push hot air outside via a hose. The window-bracket kit that ships in the box rarely fits sash, casement-with-trickle-vent, or tilt-and-turn windows without modification.
• Sealing the gap — a good install seals the window opening with foam or a custom panel so cooled air doesn't escape and warm air doesn't pour back in. Skip this and the unit struggles.
• Condensate drain — single-hose units pump moisture out through the exhaust; some dual-hose units have a tray that needs emptying or a continuous drain hose to a sink or outside.
• Power — a 12,000 BTU unit pulls around 1.1 kW. Avoid sharing the socket with kettles, microwaves or fan heaters on an old ring main.

Typical UK costs

Estimates only — prices vary by region, access and unit type. London and the South East run 15–25% above the national average for tradesperson time.

Single-hose vs dual-hose units

If you're choosing the unit yourself, this is the spec that matters most. Single-hose models are cheaper and lighter but pull room air to cool the condenser, which creates negative pressure and sucks warm outside air back in through gaps. Dual-hose models (separate intake and exhaust) are roughly 30% more efficient in real use but cost £100–£250 more. For rooms over 20 m², dual-hose is worth the premium.

Things people often miss

• BTU sizing — a 7,000 BTU unit won't cool a 25 m² south-facing room. Rule of thumb: 600–650 BTU per m² of floor area, more if the room is sunny or has a lot of glazing.
• Noise — portable units run at 50–65 dB, similar to a dishwasher. Don't put one in a bedroom unless you've checked the spec.
• Hose length — exhaust hoses should be as short and straight as possible. Long, looped or bent hoses re-radiate heat back into the room and kill efficiency.
• Listed buildings + leases — if you're drilling a wall vent for a permanent install, check freeholder/leaseholder rules and conservation status first. A reversible window kit avoids all of this.

Frequently asked questions

Do I really need a tradesperson for a portable AC?

Not for a basic plug-in setup with a standard window — that's a DIY job. You typically only need help when the window is awkward (sash, casement with trickle vents, tilt-and-turn), when you want a permanent wall vent, or when the unit needs to drain continuously to a sink or outside.

How much does it cost to run a portable air conditioner?

At 28p per kWh (the typical UK price cap rate as of 2026), a 1.1 kW unit running for 8 hours costs around £2.50 per day. Realistic monthly running cost in a hot summer week: £15–£25, depending on how much you use it.

Can I install one in a flat with sash windows?

Yes — but you'll need a custom panel cut to fit between the sashes, or a fitted board that holds the lower sash open with a sealed cut-out for the hose. Many tradespeople will fabricate one for £80–£150 from MDF or rigid foam panel.

What's the difference between portable AC and a split system?

A split system has an outdoor compressor and an indoor wall-mounted unit connected by refrigerant lines — it's quieter, more efficient and cools larger spaces but costs £1,500–£3,000 fitted and requires F-Gas-certified installers and (usually) building consent. Portable AC is plug-in, no consent needed, but louder and less powerful.

Can a portable AC heat as well as cool?

Many newer models are heat pump units that reverse the cycle to provide heating in winter — useful for shoulder seasons, though they're less efficient than a dedicated heat pump for a whole house. Check the spec sheet; the feature is sometimes labelled "reverse cycle" or "year-round".

Where should I put the unit in the room?

As close to the window as the hose allows, away from soft furnishings, with at least 30 cm clearance on all sides for airflow. Don't bury it in a corner — air recirculation drops sharply and the unit short-cycles, wasting energy.

Want a local pro to handle this? A qualified installer can size, vent and seal a portable AC properly in an hour or two — the difference between a unit that actually cools your room and one that just makes noise.