Air Conditioning Buying Guide

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Air Conditioning Buying Guide

Feeling a little lost in the world of air con? No need to sweat it—Air Con Centre is here to help.

Choosing the right air conditioner unit for your home or office can be a daunting task, especially in the UK with its varying climate and weather conditions. With so many models of air con units on the market, it is important to do research to ensure you are selecting the most suitable air conditioning system for your environment and budget.

In this guide, we will provide you with essential tips and advice for selecting the perfect air con unit. We will discuss factors such as size, efficiency, noise levels and installation requirements so that you can be confident in your choice of system. With this knowledge in hand, you should be well-equipped to choose a unit that will give you years of reliable cooling and comfort.

Your room and system size

It is essential to understand the size of your room when selecting an air conditioner. Not only will it ensure that you are buying a unit that can adequately cool or heat the space, but it also has energy efficiency benefits.


Having an undersized air conditioner can lead to problems with cooling and temperature, as the unit may struggle to maintain the desired level.


On the other hand, buying a unit that is too large for the room will result in wasted energy due to more frequent cycling on and off. In addition, having an oversized air conditioner can be noisy and uncomfortable as air might not be circulated evenly throughout the room.

For best results, it is important to measure the space accurately to determine which size option is suitable for your needs. The measurements should include the length, width and height of your room and account for any irregularities in shape, such as slanting ceilings or walls with alcoves. Our portable air conditioners collection handily sorts units by room size for you.

How powerful do I need my air conditioner to be?

Air conditioner power is measured in BTUs (British Thermal Units) and the size of your room should determine the power rating you need. The higher the BTU, the more powerful the unit will be.

As a general guide, we recommend that for every 9 sqm of space, you should select an aircon with 7,000 BTUs of cooling power. For example, if your room is 16sqm you would need a unit with at least 9,000 BTUs, and if your room is 36sqm, you'd need 17,000 BTUs to cool it down effectively.

It is also important to consider factors such as the number and size of windows in the room, the regular occupancy, and the presence of frequently used appliances. These variables can impact the BTU requirement for optimal performance.

What does BTU mean?

BTU stands for British Thermal Unit. This is a way to measure how much energy something has. For example, one BTU is the amount of energy it would take to heat up one pound of water by 1° Fahrenheit. People usually use BTUs when they talk about things that heat or cool, like air conditioners.

Room Size BTU*
Sq. ft. Sq. m
<97 <9 up to 7,000
97 9 7,000
172 16 9,000
269 25 12,000
388 36 17,000
>388 >36 17,000+

*BTUs are calculated based on the average ceiling height in the UK of 2.4m, considering 2 people and 1 appliance.

You can use our handy BTU calculator to calculate the specific BTUs required of your air conditioner for your room based on its dimensions and how the room is used.

BTU Calculator

Types of air conditioners

In the UK, there are two main types of air conditioning units. Wall mounted systems have an outdoor compressor unit and indoor fan coils that can be put in walls. Portable air conditioning units are smaller and can be moved from room to room.

image of a white air conditioner unit in a living room

Portable air conditioners

Portable air conditioners are a great addition to any home or office. Unlike wall split air conditioning, they can be placed in any room, giving you more flexibility and control over your cooling options.

To ensure that your portable air conditioner cools efficiently, you need to vent it out of a window. These units work by removing warm air from your room, and this hot air must be directed outside through the exhaust pipe. You can vent the pipe through a window, door, ceiling or wall. Make sure your purchase the correct size window kit or ducting kit for your home, if one is not included with the unit.

With a portable AC unit, you can enjoy the comfort of cool air in any room of your home quickly and easily. Overall, portable air conditioners are an efficient and convenient way to keep your home cool and comfortable, even on the hottest days of the year.

Shop Portable Units


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Easy to move around

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No installation required


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Less powerful than other types of units

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May struggle to cool larger spaces effectively

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Requires a window or door for venting

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Wall mounted systems

One major benefit of wall mounted air conditioning is that they are incredibly efficient. The units are known for their ability to cool rooms quickly and effectively without wasting any energy. The cooling systems are made to change the amount of power they use depending on how hot it is in the room. This means they only use as much energy as needed, so you don't waste energy cooling too much.

Another significant advantage of wall split air conditioning is that they are incredibly quiet when compared to traditional AC systems. This is because most of the noise produced by AC systems comes from the outdoor unit, which is placed outside so that the noise doesn't disturb those inside the house. Wall split units can also be designed to have special features, such as "night mode," which reduces the noise level even further while you're sleeping.

Shop Wall Mounted Air Conditioning Units


For installations in the UK, you will need an F-Gas registered engineer to install any wall split air conditioning unit. This includes any servicing and maintenance. This will ensure high standards of workmanship and compliance with relevant regulations.

To find local F-Gas registered installers, you can search websites such as Checkatrade or TrustATrader.


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Energy efficient

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Cools a room quickly

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Reduced noise level


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Requires professional installation

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Higher initial costs

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Fixed unit, not portable

an image of a ceiling air conditioner unit on the ceiling

Ceiling air conditioners

Consider ceiling air conditioners if you're dealing with restricted wall space in large commercial buildings. These units fit discreetly into the ceiling, distributing an even flow of cool air throughout the area. Plus, they operate quietly and are energy efficient. However, it's important to note that ceiling air conditioners come with a higher price tag and must be installed by a trained professional.

Shop Ceiling Units


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Even cooling throughout a space

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Relatively quiet and energy efficient

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Good for spaces with limited wall space


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More expensive than other types of units

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Require professional installation

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Commercial air conditioning units

Commercial air conditioning units are designed for large commercial spaces such as offices, shopping malls, and hospitals. They are powerful and can provide cooling for large areas. They are also customizable to fit the specific needs of a space, such as the number of occupants, humidity levels, and air quality. However, they are the most expensive option and require professional installation and maintenance.

Shop Commercial Units


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Powerful and customisable for
large commercial spaces

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Good for specific needs such as
humidity levels and air quality


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Are the most
expensive option

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Requires professional
installation and maintenance

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Not suitable for home use

an image of a ceiling air conditioner unit on the ceiling

Things to consider

How are you able to vent the unit?

Most air conditioning units require some form of venting, whether through a window, wall, or ductwork. Consider the layout of your space and choose a unit that can be vented in a way that works for you. If you're using a portable unit, look for one with a flexible hose that can be adjusted to fit your space.

What features are you looking for?

There are different features that come with air conditioning units. Here are a few examples:

Programmable thermostat

A unit with a programmable thermostat allows you to set the temperature and schedule the air conditioner to turn on and off at specific times, saving energy and money.

Air filtration

An air conditioner with a good filtration system can remove allergens, dust, and other particles from the air, improving air quality and reducing allergy symptoms.

Noise level

Air conditioners can be noisy, and some units are louder than others. Choosing a unit with a low decibel level can improve comfort and reduce disturbance. Some units have a Sleep Mode to reduce the noise level during the night.

Smart features

Some air conditioners come with smart features that allow you to control the unit remotely through a smartphone app, voice commands, or home automation systems.

Do air conditioners require maintenance?

Maintaining your air conditioning unit is an essential task that can greatly benefit your overall health and safety. One of the critical components of your air conditioning system is the filter, which plays a significant role in ensuring that the air you breathe is clean and free of pollutants. A dirty filter can cause your unit to work harder, which can lead to breakdowns and costly repairs. To avoid these problems, it's crucial to clean or replace your filter regularly. Remember, always follow your manufactures directions. And if your air conditioner is a wall spilt unit or commercial, you must have a F-Gas registered engineer maintain and service your unit, you cannot do this yourself unless you have the relevant qualifications.

Moreover, safety should always be a top priority when dealing with air conditioning units. Therefore, it's crucial to keep the surrounding area clear of any obstructions, such as furniture or plants, and to ensure that your unit is installed correctly. By adhering to these maintenance tips, you'll be able to keep your air conditioning unit in optimal condition and enjoy safe, pleasant air quality.

Are air conditioners safe?

Yes, air conditioners are safe to use if you follow the manufacturer’s instructions. They should be regularly serviced, and all parts of the system must be in good working order for it to operate safely. Air conditioning units also come with safety features such as auto shut-off and built-in safety sensors that will turn the unit off if the temperature drops to a certain level.

If it's a spilt wall unit, make sure your air conditioner is installed by an F Gas registered installer and that you follow all safety precautions when operating the unit such as keeping combustible materials away from the condenser and not blocking the vents. With all this in mind, make sure to take the appropriate safety precautions when selecting and using your air conditioner.

an image of a hand reaching for a remote control of an air conditioning unit

To pick the right air conditioning unit for you, you have to consider factors like space size, noise preferences, budget, and specific features that meet your needs. Wall-mounted, ceiling, or commercial units each offer unique advantages. You also have to keep in mind venting options, features, and maintenance requirements. Proper installation and maintenance extend the unit's lifespan and ensure safe, high-quality air conditions. By carefully considering these factors, you can make an informed decision when choosing an air conditioning system.