Air conditioning buying guide
Last updated: March 7, 2024
How does an air conditioner work?
Keeping cool in summer or warm in winter 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.​
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.
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
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.
Wall mounted split air conditioning system
For those unfamiliar with a split system air conditioner. This is a heating and cooling system made up of two parts, a wall mounted indoor unit called an evaporator and an outdoor unit also known as a condenser. The outdoor unit is usually mounted to the outside wall of a building while the indoor unit is wall mounted to the internal wall of the building. This is the part of the system most recognisable to most people. The indoor unit is responsible for pumping out hot air in winter or cold air in summer into the space being air conditioned. The indoor unit also filters dust, bacteria, unwanted smells as well as removing excess moisture from the air in the surrounding air.
​
Other names for split air conditioning systems include ductless air conditioning and reverse cycle air conditioning. These units are an ideal solution for heating or cooling specific rooms. Multi-split air conditioning systems allow for several internal units to be connected to just one outdoor unit, but each indoor unit can be controlled separately in different rooms within the same building. Indoor units also be of different sizes to better suit a room size or room use. Cooling only split system air conditioners are also available.
​
NOTE: The outdoor unit supplies power to the connected indoor unit. A split air conditioning system requires BOTH an indoor unit and an outdoor unit to operate correctly. The indoor unit MUST also be compatible units. You cannot mix and match a random indoor unit to an outdoor unit. If unsure speak to our friendly customer support team who will advise you.
The indoor unit and outdoor unit will usually be placed opposite each other for easy connection, just separated by an exterior wall of your home. The indoor unit of a split system will draw in the warm air in your home, cool it down, and send it out into your room. Through this process, the refrigerant in the system will heat up and transfer to the outdoor unit, where it will then be cooled down, and the excess heat will be expelled into the outside air.
​
In addition to controlling central air circulation, a split system air conditioner controls temperature, dehumidifies the air, and filters dirt and bacteria from the air. In order to regulate a constant temperature, the device removes as much moisture from the air as possible. Additionally, the system filters out pollutants and other particles that make the air dirty. Efficient air conditioning systems contribute to a cleaner home environment by allowing the occupants to keep windows and doors closed, forcing bugs, pollen, and other outdoor annoyances to stay outside. Split air conditioning systems can be wall mounted or ceiling mounted.
Ceiling cassette split air conditioning systems
A cassette air conditioner is essentially a type of split system, because it consists of two units; one inside and the other one installed outdoors. The difference with cassette air conditioners is that the indoor unit is installed in the ceiling.
​
A cassette air conditioner works much like other split systems. However, the real difference is the head unit of the cassette is mounted flush with the ceiling for a sleek look. It draws air in the centre of the head unit and cools or heats this air depending on what mode you have it set on. It will then start to condition the space immediately through a “4 way” vent system.
This means that a cassette air conditioner removes unwanted smells, pollutants, dust and excess moisture from the air, and replaces it with either cooled or heated fresh air. No ductwork is needed with ceiling air conditioners and the outdoor condenser can power more than one indoor unit, so you can install ceiling grilles in multiple rooms if required.
​
The cooled or heated air is sent downwards by powerful fans in two, three or four directions through the indoor cassette’s vents. Along with the more common square models, there are circular designs that provide 360 degree coverage, giving you balanced airflow.
Evaporative air coolers
Evaporative air coolers are a great alternative to traditional air conditioning systems and are becoming increasingly popular due to their energy efficiency and cost-effectiveness. Evaporative air coolers work by taking warm, dry air from the environment and passing it over a wet evaporator pad or ‘cooling media. This process causes the air to become cooler and more humid, making it a comfortable and pleasant environment
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. The table below shows what power (kW), you need your air conditioner to be depending on your room size.
How powerful should my air conditioner be?
To find the size of air conditioning unit required for the space you intend to cool down or heat up, you need to start by finding out area of your room in square metres or feet (we prefer square meters). This is SIMPLE. Begin by taking the length and width of each room and multiplying them together. Then, simply add the area of each room to get an answer in square metres.
​
A general formula is: Room size (m²) x 150 watts = Required air conditioner unit size (kW)
​
NOTE: This is just an estimate for what size air conditioner you need.
If you want to cool a particular room and don’t know about the right size air conditioner, please refer to the room size table.
What are the factors affecting air conditioner efficiency?
To ensure you’re cooling your house as efficiently as possible, it is imperative to get the right size of air conditioner. Although the size of your air conditioner does matter a lot, it is NOT THE ONLY FACTOR to consider when sizing your air conditioning system. For example, if your best friend or neighbour has the same sized home as yours, you might have to consider a different size air conditioner due to a shady tree or more windows facing the afternoon sun.
​
Keep in mind that the following factors could affect your air conditioner’s cooling efficiency:
-
Insulation of the home
-
How hot and humid it gets in the summer months
-
The amount of shade and/or sun your home receives on a daily basis
-
The number of windows and their design, age and insulation efficiency
-
Ceiling height, as the total air volume inside has an impact on the efficiency
-
Condition of pre-existing ductwork in your home
-
The number of residents in the room at one time
-
Roof material (tiles or tin)
​
The factors listed above can significantly affect the efficiency of your air conditioner. That is why it is crucial to take them into account before choosing the right size AC. If you have any doubts, consult with an HVAC professional who will evaluate your home and help you select the appropriate air conditioner type and size for you.
Factors to consider when choosing an air conditioner
While air conditioner size matters, it is not as important as most people think. A lot more goes into choosing the right air conditioner for your home or business than just the kW rating. In fact, you can find other factors negating the common perception that air conditioner size is everything.
​
Here is what you need to consider before selecting the best cooling solution for your home:
Air conditioning unit installation
Having your new air condition unit and equipment installed
Once you have bought your shiny new air conditioning system, it will need to be installed by a registered F-GAS installer to ensure correct and safe operation. This is a legal requirement in England and will ensure many years of trouble free operation. Most manufacturers will only provide warranty on products that have been installed by a professional f-gas certified installer.
​
Installation costs
Having your equipment installed by a professional can often cost as little as £600 although naturally costs can increase for larger systems or where there are non standard installation requirements.
​
FREE Installation quotation
At shuddle.co.uk we offer a free installation quotation with the purchase of any air conditioning equipment, to request a free installation quotation with your purchase, simply check the 'Free Install Quotation' checkbox during the checkout process and where possible, our friendly customer support team will provide you an installation quotation (terms & conditions apply).
​
Arranging your own installation
If you would prefer to arrange your own installation, you can. All you need to ensure is that whoever you decide to select as your preferred installer is f-gas registered. Any installer can install the items you purchase from buyairconditioning.co.uk, you are not obliged to use our installer even if you have requested a free install quote from us.
​
If you would like to search for an installer near you, please visit the FGAS register to search for a professional installer. Click the FGas icon below.
​
​
FAQs | Here are some frequently asked questions
Can air conditioners heat your room?
Yes, some air conditioners can serve as a heating device for your room. You can always find this information in the product details.
​
What is a BTU?
BTU means 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 (-17 °C).
​
What air conditioner BTU do I need?
To determine what size of air conditioner you need for a room, several factors need to be considered like the number of people and big appliances in the room and the amount of sunlight it gets. As a rule of thumb, select an aircon that has a cooling power of 7,000 BTUs for every 10m² of space. For a 20m² room, go for a unit with at least 14,000 BTUs. If the room is bigger than 30m² , you might need to install more than one air conditioner or go for a higher power rating.
Is it expensive to run an air conditioning?
It's hard to give an exact cost for running your air conditioning, but for example a 9000 BTU portable air conditioning will cost you on around 30p per hour. If you'd run this unit for 8 hours per day, that will add up to around £70 per month. For a more accurate estimate, check the product information and your energy costs.
How often should I have my air conditioning serviced?
It is recommended to have your air conditioning serviced at least once a year. If you use your air conditioner daily, it may be advisable to have it serviced two to three times a year. If you want more information, you can check out our air conditioner maintenance article.
​
Can I install a wall split air conditioning myself?
No, you will need an F-Gas registered engineer to install this unit for you.
How to contact us
Our friendly customer support team are happy to assist you Monday - Friday | 8:00am - 5:00pm.
​
Live chat support: Speak to our livechat team
​
Email: support@shuddle.co.uk
​
Telephone: 01234 567 890
​
(Current call wait time: Less than 3 minutes | Emails typically replied to within 24 hours of receipt)
Newsletter
Sign up to receive updates on new arrivals and special offers