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Portable air conditioners – Are they really any good?


This is a common question that we get asked here at DiO and the answer is, like most things in life, yes and no. It depends on what you define as a portable air conditioner….

The primary aim of using a portable air conditioner is to cool the air in a room or area in order to make it a more pleasant environment to live and work in.  There are principally two types of air conditioners marketed in the UK - evaporative coolers and refrigerant devices.

Let me say a few words about evaporative coolers first. These are simple self contained devices that you put water or ice into. The water soaks a membrane through which the air is passed. As the air passes through the membrane the water evaporates and this causes cooling (like wetting your finger and blowing on it – as you blow your finger cools down due to the evaporation of the water). Great I here you say….but there are issues. Firstly, these units can only operate in fresh air – i.e. with doors and windows open. Shut the room up and they will do nothing as, and this leads me on to the second point, they ADD humidity to the air. This is fine if you are in Arizona but in the UK we generally get hot muggy (i.e. high humidity) weather and these units will make the humidity situation worse not better. Finally, these units are very limited in the amount of temperature change they can make – just 2-4 degrees C across them at the most which is not going to be noticeable in a lot of cases.

So, evaporative coolers are NOT the solution for the UK climate what ever the marketing hype says - despite the initial attractions of price and convenience.

Refrigerant devices – refrigerant portable air con units are ‘true’ air conditioning units based on a sealed refrigerant circuit and a compressor. The theory of operation is identical to all commercially installed air conditioners you see today – be it in the home, office or hotel, even in your car. Refrigerant air conditioners create proper chilled air – typically 10-15C irrespective of the ambient conditions. As they cool the air they take the moisture from the air too (dehumidify) so they actually reduce the feeling of mugginess in the air at the same time as cooling it down.


Portable air conditioning units remove the heat (and most the humidity too) by exhausting it from a flexible ‘tumble drier’ type hose that is typically 125mm (5”) diameter and about 2 metres long.  Normally you would put the open end of the hose out of a slightly open window or door, through a wall vent or even up into a false ceiling. You can set the preceise temperature you want and a portable air conditioner will turn on and off automatically to keep the room temperature at that level.

Cool your lounge. Cool the bedroom down before you go to sleep. Cool the office that is overheating from the equipment and big sunny glass windows. Cool the shop where people leave quickly without buying as it’s too hot – just watch how people ‘hang around’ in air conditioned cool, dry, fresh areas. 


A correctly chosen portable air conditioner will work just as well as a fully installed system – after all the technology inside is identical – and will do so with the advantage that they can be wheeled on castors from room to room as needed.

When the weather is cooler you can simply park them away in a cupboard until the next time you need them.
Portable, instant chilled air on demand – a refrigerant portable air conditioner is an excellent solution to the hot muggy summer weather we do get in the UK.

Now everyone says it’s going to be a hot summer …