Choosing The Right Sized Split System For Your Home This Winter

Before forking out the money to get a split system air conditioner for your home – make sure to choose the right size for your space. We can’t tell you how many times we’ve encountered customers complaining about their brand new split systems not working properly only to find that it’s the wrong size for their home. 

But don’t worry, we’ve got you covered. First, let’s take a look at air conditioner sizing. 

Understanding Air Conditioner Sizing

Air conditioner sizing is calculated based on the power or capacity (kilowatt or kW) it is able to provide and not its physical appearance. In fact, you could have air conditioners that look similar but provide different capacities.

Selecting the right sized air conditioner for your home is probably the most important decision to make when purchasing an air conditioner. 

An oversized unit could cause you to incur a higher electricity bill and suffer from overheating of the space. However, an undersized unit would mean that it cannot sufficiently heat your space and would need to work extra hard. This can overwhelm the system and over time cause it to wear down further.

So how do you decide? 

Here are some factors to consider:

  • Area
  • Current insulation available
  • Climate (extreme weather)
  • Orientation (where your house is facing)

Factors That Impact Air Conditioning Sizes


As a general rule of thumb, the bigger the area, the higher the capacity needed to effectively heat the space. 

A larger room or space would require more powerful airflow to effectively heat the entire area. You can refer to the following guide on how much capacity is required for your rooms:

Room Size Description Estimated Capacity
Small (up to 20m2) Small kitchen, bedroom, study 2 – 2.5kW
Medium (20 – 40m2) Small lounge, bedroom with adjoining bathroom 2.5 – 5kW
Large (40 – 60m2) Mid-sized lounge, large bedroom or kitchen  4 – 6kW
Extra large (60+m2) Large lounges, open-plan areas 5 – 9kW

BUT area isn’t the only factor to consider.


Insulation helps to reduce the amount of heat loss by retaining heat in your home. A well insulated home will ensure you get your money’s worth from your air conditioning system. However, if your home is poorly insulated you may need to get a stronger split system air conditioner to compensate for the energy loss. 

There are a few ways you can insulate your home to help maintain the temperature indoors.

These include:

  • Drawing your curtains or shutters closed 

This would help keep the heat indoors from escaping during winter. Similarly, during summer this would help prevent sun rays and heat from getting inside. It is a simple fix and if done tastefully can enhance the appearance of your living space. 

  • Installing double glazed windows

Double glazing refers to creating a pocket of air or gas between the glass that functions as a buffer and resists heat flows. Double glazed windows are great for reducing heat build up during the summer months or heat loss during winter months.

  • Insulate around plumbing pipes

Insulating your plumbing pipes can help to reduce the heat loss to the surrounding air. This can also help you save on energy loss and the resulting energy bills. An added plus to insulating your plumbing is that it can reduce the noise coming from the pipes


Melbourne is known for its extreme weather. One second you’re enjoying the sunshine and the next you’ll be running indoors for some warmth. 

Extreme Weather

If you’re residing in a location that experiences extreme weather conditions, you may want to consider getting a stronger or bigger split system. 

This is to ensure that your system is able to keep you sufficiently warm through some of the most unexpected weather conditions, such as when Melbourne’s winter temperature dips below zero. 

Temperate Weather 

If weather conditions do not fluctuate much, you can follow the average guides and sizes recommended at the beginning of this article. Those guidelines should be sufficient to effectively heat your living space. 


The orientation of your living space and rooms matters as it will determine how much energy you would need throughout the day. Does your room or living space get the morning or evening sun? 

Say for example your room is cool throughout the day but you’re at work – you wouldn’t really need air conditioning during this period. However, if your room gets cold and you’re working from home, you would need to factor in using your air conditioning throughout the day. 

Why Choosing The Right Size Matters


Just looking at the picture above, you can see how large the space is and how there are two air conditioning units there because one simply isn’t enough. 

There’s no point in purchasing an air conditioning unit that doesn’t effectively heat your space. You’re better off using something that fits your space well.


As we mentioned earlier, if you purchase an air conditioning unit that is too small for your space, it will eventually overwork the system which can wear it down earlier than expected. 

If the unit is too big for your space, you’d be spending too much on your energy bills. So getting the sizing just right is the way to go.

How Much Will It Cost?

Air conditioner installation costs can range from anywhere between $2,000- $6,000 (including cost of the air conditioning unit), depending on the type of system you’re installing and how complex the works will be

Upfront Costs

Small split systems can cost between $700 to $1,500 depending on the brand and model. Larger split systems on the other hand can cost up to $4,000.


Capacity Estimated Price Range
2.5 kW – 3.5 kW $700 – $1500
5 kW – 9 kW $1000 – $4000

While split systems may cost a fair bit upfront, they will save you more over time compared to other heating systems because of their lower running costs.

There are several other factors that would impact the final price of your split system such as the brand you go with and if the installation is a replacement of an older air conditioning unit. Get a split system quote estimate from Gaschill to get a better idea of what you need. 

Choose The Right Sized Split System For You

We’ve discussed what factors you should be considering when deciding on what split system air conditioning unit to choose for your home. The answer may not always be as clear cut but this way, you have an understanding of what to look out for. 

If you’re still unsure or you have more questions, feel free to speak to one of our Gaschill technicians. We’re more than happy to help.