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What size air conditioner do I need for my home?

What size air conditioner do I need for my home?


Some of the most common questions we get asked here at Acer Services relate to air conditioning sizing. Standard split systems can range from 2.0kW for a small unit and up to 9.5kW for a large, powerful unit. With such a wide range of capacity available, it’s very important you choose a unit that will sufficiently cool the required area. 

Essentially, you need to ensure your unit has enough kW to cope with the hottest day of the year. There’s nothing worse than sweltering through 42 degrees on Christmas day with all the family around because the air con can’t keep up with the heat.

With an undersized air conditioner, the compressor has to work overtime to keep the room at the set temperature. Compressors are meant to stop after a period of time in order to cool down, but if the unit is struggling, the compressor won’t stop. A compressor in an undersized air con will wear out more quickly if it’s regularly prevented from cooling down properly.

Some people think that the best thing to do is just get a really big unit so they don’t ever have to worry about the air con struggling in summer. But a unit that is oversized for the room it is installed in will simply chew up lots of energy, causing your power bills to sky rocket. Also, an oversized until will blow too much air around in proportion to the room size which can make being in the room feel very uncomfortable.

The wrong size air con can also affect your warranty. If you try to make a warranty claim and your unit is oversized or undersized, the manufacturer may determine that the unit is ‘not fit for purpose’ and refuse to accept your claim.

What you need to find is the “Goldilocks” factor. You need a unit that is not too big and not too small, but just right for your needs and the size of your home.

But determining what size unit you need is not always straightforward. There are many factors that need to be taken into account.

Let’s take a look at some of these factors…

Facing West. If the room you want to install an air con in is on the Western side of your home, you’ll want to think about getting a bigger unit to cope with the extra heat as the sun heats up the room from the afternoon onwards. This is even more important if the configuration of your home requires that the unit has to be installed on a Western wall.

Lots of glass. Rooms that have multiple floor to ceiling windows or glass doors are going to let in A LOT of heat. Modern home designs tend to feature lots of glass in the living room and this is something people commonly overlook when they are figuring out what size air conditioner they will need. So the more glass there is, the more kW you’ll need from your unit.

Open plan. Many homes feature an open plan style kitchen and lounge room. If you want air conditioning in your lounge room and there’s no way for you to close off air flow to the kitchen, then you will need to consider the total sqm of both your kitchen and your lounge room. If you base the amount of kW you need solely on the sqm of your lounge room, the unit will seriously struggle to keep the area cool. The more sqm there are, the bigger your air conditioner will need to be.

Age of your home. Older homes are generally hotter because they lack some of the cooling and energy saving design features that have become standard in modern homes such as insulation, eaves and tinted windows. Many people with older style houses (e.g. Queenslanders) will invest in adding these cooling properties, but there are sometimes design flaws that can’t be overcome, such as the orientation of the house and a lack of shade.

Insulation. If your home is insulated, you’ll definitely save some money on your power bills. That extra cooling will help you avoid needing to run your air conditioner at low temperatures all the time through the hot Summer months. In terms of how insulation affects what size unit you’ll need, you may be able to get away with going down one unit size. But always remember to look at your house as a whole and see if there are other factors that necessitate the need for additional kW (e.g. orientation, ability to close off areas that need to be cooled).

So what size air con do I need?

As we’ve covered, there are a lot of factors that contribute to how easy or difficult it is to keep your home cool.

Some air conditioner retailers and installers will recommend certain air con sizes simply based on the sqm of a room. But in our experience, there’s no real “rule of thumb” that can be applied to air conditioning sizing. The unique properties of your home and the placement of your air con needs to be carefully considered.

If you have been given an initial idea of what size unit you need, our advice is to always go up one size in kW. This way you can be confident your unit will function perfectly on the hottest days of the year while still avoiding having a unit that is way too large.

The very best way to accurately determine what size air con you need is to have a trained technician conduct an inspection of your home. They know exactly what to look for in terms of factors that will directly influence the efficiency of your air con and will make an expert recommendation on what size unit you’ll need to stay cool and comfortable all Summer long.  

Top Tip – reducing your power costs

If you do need a high kW unit to keep your home cool but are concerned about your power bills, an air conditioner with Inverter technology is the way to go.

Inverters work to maintain the set temperature without needing to run at full capacity. Once the room is cool, the compressor will slow to the desired speed to maintain the temperature. This helps you lower your electricity consumption and that means you save money.

There are also plenty of other ways to reduce your air con running costs such as installing tinted windows, always closing the curtains when operating the air conditioner and adding insulation in your ceiling.

Want expert advice on the right size air conditioner for your home? Just ask Acer Services!

Like with every air conditioner we install, our technicians will carefully inspect your home, measure the required areas and make some expert suggestions in relation to unit size and placement. Like our motto says…the difference is the detail!

For more expert help and advice, talk to one of our friendly, helpful team members.

Simply click here to get in touch.


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