Two types of system are available – single units and split systems.

Single Units
These are the simplest units and have an exhaust hose which is used to expel the hot and damp air to the outside. Single units can cope with a wide range of room requirements

Split Systems
For larger rooms or rooms that have bigger heat loads split systems are normally required. These have a separate, fairly large condenser box that needs to be placed outside the room.

How the heat is expelled:

Single Units
This is achieved by means of a short flexible hose which is vented through an outside wall or window..

Split Systems
The separate external condenser box is connected to the main inside unit by means of refrigerant lines. These lines can be passed through a hole in the wall, about the size of half a brick before reconnecting. The external box can then be positioned on the ground outside or if not at ground level, can be hooked by straps over the edge of a window frame.

It’s important that you buy the right unit. You should consider these factors before you decide on a unit that’s right for you:
Calculate the cubic capacity of your room to find out how powerful a unit you need.
Before you choose a portable air conditioner, the first thing you should consider is how large of an area you’re trying to cool. UK portable air conditioners are rated in BTUs, or “British Thermal Units.” Most portable units range from 5,000 to 15,000 BTUs. The higher the BTU rating, the more powerful the unit

You need to make sure that the unit you buy will do the job adequately for the room. Hovever there’s no benefit in getting a more powerful unit than required.

You should also pay attention to the portable air conditioner’s Energy Efficiency Ratio.

The higher the EER, the more energy-efficient the portable AC unit. The current minimum requirement by law is an EER of 10. Purchase a model with the highest EER you can reasonably afford because this will eventually save you money on your energy bill.