Air Conditioning Buying Guide

Air Conditioning Buying Guide

Updated by Alex Wells on

Keeping cool, especially in the summer months can prove to be a challenge even in the UK. Take back control of the temperature and get a good night’s sleep by investing in an air conditioning unit. But which one is right for you? Our guide will help you navigate the many options available to you.

When buying an air conditioner there’s a lot to consider. The room size, number of windows, noise levels, connectivity options and price all play an important factor when deciding on the right unit.

In this buying guide, we’ll look at everything you need to know when deciding which air conditioner is right for you.

If you just want to know our favourites, check our our Top 10 Portable Air Conditioners

Image of an aircon in a nursery

Firstly, how does an air conditioner work?

When an air conditioner is switched on, internal fans draw air into the unit and over a cold evaporator coil. The excess heat is absorbed by a chemical refrigerant which cools the air and removes some of the moisture. The cooled air is then recirculated into the room. This process reduces the overall temperature and humidity. Hot air is vented outside through an external hose.

Once the desired temperature is reached, the air conditioner will automatically switch off. When it detects the temperature rising again, it will switch back on to maintain the desired temperature.

How powerful should an air conditioner be?

The power of an air conditioner is measured by its British Thermal Unit rating, or BTU. The higher the BTU, the bigger the room the air conditioner can cool. However, a higher BTU can also mean higher running costs, size and noise.

Table explaining the capacity of different aircon units

This table shows what BTU and power kW you need your air conditioner to be depending on your room size.

Does an air conditioner need to be vented?

The venting requirements of your air conditioning unit will depend on it’s type. All portable air conditioning units will need to be vented using a ducting hose, whereas split wall units will have an outdoor component that will take care of this.

A portable air conditioner should be vented directly outside, as this allows the hot air to be removed as fast as possible. If this isn’t possible, it can be vented through a slightly open door into another room or corridor, but this is not ideal as it simply moves the hot air around your home.

Different types of air conditioners

Portable air conditioners

Example of a Devola portable air conditioner

A portable air conditioner is the most popular type of air conditioning unit found in homes or any situation where you need a versatile option.

They can be easily moved to wherever you need convenient cooling, from room to room and even between floors.

Some units include an external ducting hose, whilst others do not, so you will have to check. If the unit does not include a ducting hose, you will need to purchase one separately. The ducting hose will need to be vented outside, so be sure to pick a suitable location near a window. The length of this hose is generally between 1 – 1.5 metres. Avoid the temptation to extend the hose as this can cause heat to back up inside the unit, which can be dangerous.

The benefits of portable air conditioners

  • Portable air conditioners are powerful enough to cool most room sizes
  • They can be easily moved and repositioned
  • They are straightforward to setup and operate
  • You do not need professional installation
  • New units can be controlled by Smartphone via an app
  • Cost effective way to get air conditioning in your home
  • Some units offer both heating and cooling functions

Wall split air conditioners

Example of a panasonic wall split air conditioner with remote

Wall split air conditioners consist of an indoor unit and an outdoor compressor. The indoor unit is wall mounted and connected to the outdoor unit via a pipe. The outdoor unit can be installed wherever it has space, either on an external wall or floor. 

Wall split air conditioners are not mobile and will require professional installation, but they help to clear valuable floor space and are quieter to run than portable units. They are a great choice for modern open plan extensions, conservatories/orangeries, and commercial properties.

As an additional benefit, wall split air conditioners also have a heating function.

The benefits of wall split air conditioners

  • Quieter solution than portable units
  • More efficient than portable units
  • Better cooling output
  • Do not take up floor space
  • No visible ducting in the room
  • No window venting kit required
  • Remote, app, or voice control options

Ceiling cassette air conditioners

Example of a ceiling cassette air conditioner

Ceiling cassette air conditioners are very similar to wall split units in that they have an indoor unit and an outdoor compressor, but they are mounted to the ceiling rather than the wall.

The benefits of wall split air conditioners

  • Quieter solution than portable units
  • More efficient than portable units
  • Better cooling output
  • Do not take up floor space
  • No visible ducting in the room
  • Can be installed further away from external walls
  • No window venting kit required
  • Remote, app, or voice control options

Air Conditioning Features

Many air conditioners come with additional settings like:

  • Adjustable Thermostat
    This feature gives you full control over your desired room temperature
  • Timer
    The timer function allows you to control when the air conditioner switches on and off
  • Fan only
    Many portable air conditioners have a fan only mode which means you can use them as only a fan if you simply want a breeze
  • Choice of fan speeds

Use your air conditioning unit as a fan and control the desired fan speed

  • Wi-Fi compatibility
    New, high spec air conditioners have Wi-Fi technology which allows you to have complete control of your unit from an app on your phone
  • Dehumidifier only
    All air conditioners dehumidify their environment by default, meaning they will remove excess moisture from the air as well as cooling it
  • Heating
    Some newer portable air conditioners also have the added ability to heat your room, making them ideal for use all year round. 3 in 1 technology means they cool in the summer months, heat in the colder months, and dehumidify all year round.


All filters, air intakes and grilles will need to be regularly cleaned to help your unit to keep running smoothly. Filters can get dirty quickly, so it’s important to replace them or clean them regularly. You should also check that you are consistently emptying the unit’s internal water tank to avoid any leaks and possible damage.


There are a lot of things you need to take into consideration when deciding what air conditioner will work best for your needs, but we hope that this article has given you all the information you need!