Portable air con vs fitted split - the honest comparison

Portable air conditioners get a bad reputation from air conditioning professionals. Fitted splits get oversold as the only real answer. Both takes are wrong. Here is when each one is the right call.

What each one actually is

Portable air conditioner - a self-contained unit on wheels with an exhaust hose that vents hot air out of a window. Everything - compressor, evaporator, condenser - is inside the box. Plug it in, sit it in the room, run the hose out.

Fitted split system - two units connected by refrigerant pipes. Indoor head on the wall pushes cool air. Outdoor condenser sits outside the building and dumps the heat away. Requires F-Gas certified install.

Head-to-head comparison

Upfront cost

• Portable: £300 to £600 depending on cooling capacity
• Fitted split: £1,800 to £2,800 for a single room

Fitted is five to eight times the price. That is the biggest gap.

Cooling power

• Portable (9,000 to 12,000 BTU units): drops room temperature by 3 to 5 degrees on a hot day
• Fitted split (2.5 to 3.5 kW): drops room temperature by 8 to 12 degrees, faster

Fitted cools twice as much, twice as fast.

Running cost per hour

• Portable: 25 to 40p per hour
• Fitted split: 12 to 20p per hour

Fitted uses about half the electricity for more cooling. Because the compressor is outside, it does not fight against its own waste heat.

Noise inside the room

• Portable: 48 to 55 dB (conversation-level)
• Fitted split: 19 to 26 dB (whisper-level)

The gap is huge. A portable in a bedroom is uncomfortable overnight.

Install and disruption

• Portable: unbox, plug in, done - 15 minutes
• Fitted split: full day, wall drilled, F-Gas certified engineer

Winter heating

• Portable: usually cooling only. A few models heat but poorly.
• Fitted split: heats to about minus 15 degrees outside. Cheaper per unit of heat than gas central heating for one room.

Lifespan

• Portable: 4 to 6 years
• Fitted split: 12 to 15 years

When a portable is the right buy

Four scenarios:

1. Renting with no landlord permission. Portable works, portable leaves with you when you move.
2. Occasional use in a spare room or a workshop. If you only need cooling ten days a year, a £400 portable is fine.
3. Bridging the gap until a fitted install can happen. Book the fitted install for October, buy a portable for the summer heatwave.
4. A room where a fitted install is genuinely not possible - basement, mid-block flat with no external wall.

When a fitted split is the right buy

Four scenarios:

1. Primary bedroom used every night. The noise gap alone justifies fitted.
2. Living room used most evenings. Fitted cools more, faster, cheaper to run.
3. Home office you work from full-time. Concentration in a hot room is impossible - fitted pays for itself in productivity.
4. Any household where the yearly usage is more than 30 days. Break-even against portable running costs falls inside three years.

The math that surprises people

A £400 portable running 4 hours a day for 40 hot days a year costs about £58/year in electricity. Over 12 years (three portables) that is £1,200 upfront plus £700 in electricity = £1,900.

A £2,200 fitted split running the same pattern costs £2,200 upfront plus £360 in electricity over 12 years = £2,560.

The fitted split costs £660 more over 12 years. But it also heats the room for 60 to 90 days a year, saving £150 to £300 a year on gas. That comfortably offsets the difference.

For a “cooling only” comparison the portable wins on total cost. For a “heat and cool” comparison the fitted split wins comfortably.

What NOT to buy at any price

Two categories to avoid entirely:

• Cheap “portable air conditioners” under £250 sold at big high-street chains. Undersized for a UK living room. Loud. Break in two years.
• “Air coolers” (evaporative coolers) that use a water tank instead of a compressor. These do not cool - they add humidity. Useless in a UK damp climate.

If the label does not say “air conditioner with a compressor” - and it does not have an exhaust hose - it is not really cooling.

Get three quotes for the fitted option

If you are ready for a fitted split system, fill in the quote form. Three fixed prices back within 24 hours.

If you want a portable for this year and a fitted install for next, mention “next spring” in the comments and we will note it on the enquiry.