Air conditioner buying guide

Air conditioner buying guide

Kate, Flooring Expert, Swansea

Guide written by:

Kate, Flooring Expert, Swansea

Air conditioners are used to breathe cool air into our homes on hot days. But reversible systems can also work as heating! So what kind of air conditioner should you go for and what is there to look out for in terms of power, performance and installation? Read on for all you need to know about air conditioners.

Important features

  • Monoblock air conditioners
  • Split air conditioners
  • Cooling capacity
  • Energy performance
  • Air treatment
  • Installation and care
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Air conditioning: the basics

Air conditioner buying guide

Just like fridges, air conditioners use refrigerant fluid to shift the heat from inside a building outdoors. However, if you go for a reversible system, the device will also be able to take heat from outside and use it to warm up your home.

There are two main types of air conditioning systems: monoblock and split air conditioners. Monoblock systems are less powerful and noisier, but they are cheaper. Split systems are more powerful and are able to cool down several rooms, but are more expensive.

There are a few more factors to take into account including the cooling capacity of the device (which must be suited to your needs) and its energy rating to prevent your air conditioner from using too much electricity. You'll have to think about noise level and any additional air treatment options you might need.

Finally, it's important to consider how easy the indoor and outdoor units will be to install and maintain.

Different types of air conditioners

As mentioned, there are two main types of air conditioners: monoblock and split systems.

Monoblock air conditioners

Monoblock air conditioners

Monoblock air conditioners, as the name suggests, are made up of just one unit which contains the entire refrigerant circuit. These devices can simply be placed in the room that needs to be cooled and the warm indoor air will be sent out through a flexible hose. This hose can be installed through a special vent if you have one; otherwise, it can be inserted through an open door or window.

Designed to cool smaller spaces (up to 30 m2), monoblock air conditioners are inexpensive to buy and easy to install. However, these devices are fairly noisy and won't be able to cool down large rooms.

Split air conditioners

Split air conditioners

Split air conditioners feature two units: one indoor unit which can be freestanding or wall-mounted and an outdoor unit. The two units are connected via slim cables and pipes.

Multi-split air conditioners feature several indoor units which can be used to cool larger spaces or a number of different rooms.

While they are more discreet, less noisy and more powerful than monoblock air conditioners, split air conditioners are costlier.

Reversible air conditioners

Reversible air conditioners work in the same way as classic systems but are also able to reverse the cooling cycle to produce warm air in addition to cold.

Just like air to air heat pumps, split air conditioners take calories from the outside air to heat up the air indoors. Please note: these systems are highly complex and must be installed by a professional.

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Split heat pumps

Wall or portable air conditioners

Wall air conditioners

Wall air conditioners

Wall air conditioners are designed to stay in the same spot – you won't be able to move them around. If you have a split system, the pipes and cables can be hidden away behind a partition wall or in a suspended ceiling.

Portable air conditioners

Both monoblock and split air conditioners can be portable. As monoblock air conditioners consist of a single indoor unit, they can simply be mounted on wheels. Split conditioners can be made up of two portable units in which case they are connected to each other via flexible cables that can be disconnected. That said, split air conditioners are quite difficult to move around.

How to choose the right air conditioner

When deciding on an air conditioner, there are many factors to bear in mind including cooling capacity, coefficient of performance, noise level and dehumidifying rate.

Cooling capacity 

The cooling capacity of an air conditioner is measured in British Thermal Units or BTUs (1 W = 3.414 BTUs). Cooling capacity determines the how well an air conditioner can cool a particular space.

If your air conditioner lacks power, it will have to be switched on for longer and it will struggle to perform as expected. On the other hand, if you go for too much power, the air conditioner will use up energy unnecessarily.

To calculate how much power you need, it's a good idea to use your home energy certificate which will help you to think about the volume of your rooms as well as factors like glazing, sun exposure and insulation.

As a basic guideline, you'll need at least 100 W per m2 or 50 W per m3. For example, to cool a room measuring 20 m2 with a ceiling height of 2.5 m, a minimum of 2500 W is recommended (20 x 2.5 x 50).

Energy performance


There are a couple of different performance indicators to think about when it comes to energy.

  • Coefficient of Performance (COP): this refers to the ratio between the amount of energy consumed by an appliance and the cooling power of the appliance (or heating power in the case of reversible systems). The higher the COP, the less energy the air conditioner requires to cool the room.

  • Energy labels run from A+++ for the most efficient appliances down to G for the least efficient devices.

Noise level

Noise level is indicated in decibels (dB) and refers to the amount of noise that an air conditioner makes.

  • Monoblock air conditioners are the noisiest models with a noise level of 50 to 75 dB. This level can be bothersome especially at night – it's worth noting that 70 dB roughly corresponds to the noise of a busy street!

  • With split air conditioners, the unit that contains the compressor is kept outdoors. These units also produce less noise (around 45 to 55 dB) making them the quietest option overall – even though they are more likely to disturb your neighbours.

For quiet nights, go for a model with a silent or sleep mode. That said, your air conditioner will get quieter as you reduce the settings. The lowest settings can be as quiet as 20 dB which is roughly the same level as a quiet conversation.

Air treatment


Air conditioners may also be designed to treat the air in addition to cooling it.

  • Some air conditioners are also designed to work as dehumidifiers. However, the efficiency of these devices varies from model to model. The dehumidifying capacity of a device is measured in litres per day – the higher this rate, the better the device will perform.

  • It is also possible to find models with activated charcoal air filters designed to combat bad odours or electrostatic filters to fight bacteria and dust.

  • Air conditioners with a fan mode can also perform as a fan in that they will move air around without actually cooling down the space.

  • Ionising mode is used to add negative ions to the air for a purifying effect.

Remote control

Remote control is a really handy option if you want to control your air conditioner without having to get up every time you want to change a setting.

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Portable air conditioners

Air conditioner installation and maintenance


Correct installation involves finding the perfect position for your indoor and outdoor units to allow them to work as efficiently as possible.

Bear in mind that you don't want your air conditioner to be blowing cold air directly at you. Split wall-mounted air conditioners should be installed as high up as possible as long as performance is not affected. At the same time, they need to be accessible so you can carry out routine care.

Choosing the right spot for an air conditioner

3. Install the outdoor unit

The outdoor unit must be placed in a clear space. It cannot be installed in a shed or shelter but must be protected from direct sun and strong winds. As these devices can be noisy, try not to install the air conditioner too close to any bedrooms or your neighbours.

Air conditioner maintenance

1. Position your indoor unit

If you want your air conditioner to run smoothly, it is essential to carry out a few basic maintenance checks on a regular basis. The air filters must be cleaned regularly and the fan needs to be dusted. The water tray must also be emptied from time to time.

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Guide written by:

Kate, Flooring Expert, Swansea

Kate, Flooring Expert, Swansea

Flooring is my life. I love what I do, and I've been doing it for as long as I can remember. So, I'm not bragging when I tell you I know all there is to know about every flooring product. From laminate, parquet and linoleum to PVC, carpeting and tiling, my workdays are spent learning about manufacturing processes, composition, performance, laying techniques and maintenance methods. I've certainly seen my share of mistakes made on construction sites because of what was essentially a lack of information or understanding of the product. Flooring elements are constantly evolving and being improved upon - even us pros can find it hard to keep up! Some of us in the industry use language that is overly technical or loaded with jargon you'd have to be an expert to understand. What's more, flooring salespeople are often so focused on closing the sale that they don't take the time to explain the products in any detail. That's why I want to pass on my knowledge in a way that's clear and accessible, and maybe a bit fun too. Because flooring shouldn't be a chore!

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