Common mistakes when installing an air conditioner at home (and how to avoid them)

Installing an air conditioner seems easy: you choose one, install it, and that’s it. However, for many it ultimately comes at a higher cost (both financially and in terms of discomfort) if not done correctly from the outset. If you’re considering installing a new unit at home (or you’ve been thinking about it after the last heatwave), here are the most common mistakes you should definitely avoid. 

What does this article cover?

• 1. Choosing an air conditioner without accurately calculating its power
• 2. Placing the indoor unit in the wrong location
• 3. Neglecting insulation of the property
• 4. Neglecting the air conditioner's drain pipe
• 5. Installing the outdoor unit in a poorly ventilated place
• 6. Installing without a qualified professional
• 7. Neglecting maintenance
• What are the consequences of poor installation?

1. Choosing an air conditioner without accurately calculating its power

A common mistake when installing an air conditioning system is focusing solely on the unit’s price or size without considering the specific needs of your space. If you select a unit with insufficient power, it will not cool the room effectively and will constantly run at maximum capacity, consuming more energy. Conversely, if the unit has excessive power, it will consume more energy than necessary, cycle on and off frequently (which shortens its lifespan), and may dry out the air.

To avoid this, you need to take into account:

• Room size (sqm)

• Orientation (is it exposed to direct sunlight?)

• Number of people using it

• Insulation of the property

Helpful tip: A rough guide is 100 frigories per square metre, although we always recommend carrying out an independent thermal study or using online calculators from trusted brands.

2. Placing the indoor unit in the wrong location

It may seem like a small detail, but it isn’t. The location of the indoor (split) unit directly affects comfort and system efficiency. Positioning it directly opposite the sofa, bed, or dining table might seem sensible for direct airflow, but it can actually be counterproductive.

Why? Because cold air blowing straight onto the body can cause discomfort, muscle aches, or even respiratory problems. Also, if the split unit is installed in a space with poor air circulation or obstructed by large furniture or heavy curtains, the air will not be distributed evenly throughout the room.

Helpful tip: The ideal location for a split unit is on a wall free from obstructions, about 2 metres high, with the airflow directed towards the centre of the room to ensure natural circulation.

3. Neglecting insulation of the property

Even with the best system on the market, if your home struggles to retain the temperature, you will merely be cooling the air... only for it to escape through the windows. Thermal insulation is key for the unit to run, consume less, and cool better.

Single-glazed windows, metal frames without a thermal break, doors that don’t close properly, gaps… all these add up (or rather, subtract). 

Helpful tip: If renovation is not an option, begin with simple measures before installing your air conditioner: use draught excluders on doors and windows, thermal curtains, rugs in winter, and keep blinds closed during the brightest hours. Small gestures that can make a big difference. 

4. Neglecting the air conditioner's drain pipe

Air conditioning units produce condensation (water) as they cool the air. This condensation must be drained correctly, which means planning the drain’s route from the outset. 

Many makeshift installations result in pipes dripping onto balconies, inner courtyards, or, worse, onto exterior walls, causing dampness and disputes with neighbours. 

Helpful tip: The drainpipe must be sloped and carry the water to a suitable drain. If this isn’t possible, condensate pumps can be used to resolve the issue. A good installer will take this into account from the very beginning. 

5. Installing the outdoor unit in a poorly ventilated place

The outdoor unit (which houses the compressor) is the part that works hardest and needs good ventilation to release the heat it extracts from indoors. If installed in an unventilated enclosed space or near obstacles, the unit will work harder, overheat, and may have a shortened lifespan.

Access for maintenance and compliance with local regulations regarding noise and installation on exterior walls (particularly in apartment buildings) must also be taken into account.

Helpful tip: Choose a well-ventilated location, preferably shaded and clear of any surrounding obstacles. Also, verify whether permission is required for installation in certain areas.

6. Installing without a qualified professional

It may be tempting to ask a handy friend for assistance or attempt a DIY installation by watching tutorials. Installing an air conditioning system is not a game. It demands technical expertise, specialised tools, and, above all, adherence to current legal regulations, especially those concerning refrigerant handling.

Poor installation can prove very costly: from voiding the warranty through to breakdowns that are not covered by the insurance policy.

Helpful tip: Ensure your installer is authorised, always request an invoice and installation certificate, and retain all documentation in case you need to make a warranty claim. 

7. Neglecting maintenance (and then wondering why it doesn’t cool)

After installing the air conditioning system, many people forget about the unit… until it starts to give off unpleasant odours, fails to cool properly, or starts leaking. Air conditioning requires regular servicing, just like a car. Cleaning filters, checking the refrigerant, inspecting the connections… all these affect its performance and longevity.

Helpful tip: Arrange a professional service at least once a year, ideally ahead of summer.

What are the consequences of poor installation?

It may seem like just poor performance… but the consequences of a poor installation can be far more serious:

• The unit doesn’t cool or heat as it should, causing frustration.

• Higher electricity consumption, meaning bigger bills. 

• Annoying noise or vibrations, especially if the outdoor unit isn’t secured properly.

• Premature compressor breakdowns or refrigerant leaks.

• Humidity problems, leaks, or even damage to other properties.

• Loss of warranty, if the work is not done by a certified professional. 

And, if you live in an apartment, you may face disputes with neighbours or your insurance provider. All as a result of trying to save too much on installation.

Why trust Daikin?

Daikin is more than just an air conditioning brand: it sets the standard for efficiency, innovation, and reliability. And what does this mean for you?

• You can rely on a network of professional installers who understand how to optimise each system.

• All products are designed to last and adapt to the actual needs of homes. 

• Its systems come with proprietary technologies (such as inverters, motion sensors, and Internet connectivity), so all you have to worry about is enjoying your comfort.

• And all this is backed up by a warranty, after-sales service, and personalised attention.

With Daikin, you know you’re not just buying an air conditioning system. You’re investing in a climate control solution designed for your daily life. No surprises, no shocks, no unnecessary heat.

A well-installed air conditioner is like a bespoke suit: it performs better, consumes less energy, and makes your life more comfortable. Avoiding the most common mistakes can save you time, money, and a great deal of frustration.  

My final advice? Trust those who have been caring for home comfort for decades. And when the next heatwave comes, you’ll already be cool… and calm.