What Size Ducted Air Conditioning System Do I Need?

Choosing a perfect-sized ducted air conditioning system can be overwhelming, especially when you don’t know about home size, cooling capacity, suitable conditions in which it will work, and much more. So before you make the purchase, it’s worth knowing what size ducted air conditioner you need for your home.

Ducted refrigerated air con is one of the most prevalent types of air conditioning in Melbourne. This powerful and efficient form of cooling is well suited for cooling large spaces. If you’re installing a ducted refrigerated AC in your home, it is crucial to get the right size the first time. After all, it could be expensive and time-consuming to change the system once it’s installed.

Learn More: What Is Ducted Refrigerated Air Conditioning and Pros & Cons of Ducted Air Conditioning.

How To Calculate Ducted Air Conditioner Size?

Here are two steps you need to follow in order to calculate an estimated size of a ducted air conditioning unit:

Step 1

First, you need to calculate the floor area of your daytime living areas (kitchen, lounge, stairs, hallway, family room, etc.) to be able to determine ducted air con size. You have to calculate daytime living areas because you will be spending most of the daytime there instead of the bedrooms, which become cool at night due to heat load reduction.

Step 2

Measure the ceiling height and multiply it with the total daytime living area. The formula is:

Daytime Cooling Area (m²) x 150 watts = Size Capacity Required (kW)

If the ceiling height is about 2.4 metres, multiply the cooling area by 150 watts. If it is 2.7 metres, multiply by 160 watts. If the ceiling height exceeds 2.7 metres, multiply the daytime cooling area by 175 watts.

Example: If the daytime cooling area is 100 m2, the size of your ducted air conditioner would be 100 m2 x 0.15 = 15 kW.

Please note that this formula should only be used as an air conditioner size guide. For accurate size, you would have to consider other important factors such as roof insulation, overall insulation level of your house, window covering, local climate, the number of occupants, and rating of ducted insulation.

Note: You can also use the Air Conditioning Size Calculator for an estimated size.

When To Select A Large Capacity Ducted Air Conditioner?

You may want to consider selecting a large capacity ducted air con if:

  • The windows in your house are big and facing west
  • You have a big family, and occupants spend most of the time in living areas and bedrooms during the day
  • Your home isn’t insulated

When To Select A Smaller Capacity Ducted Air Conditioner?

You may want to consider selecting a smaller capacity ducted air con for your house if:

  • Your home is fully insulated
  • You spend most of the daytime outside
  • You have a small family
  • There is high-rated ductwork installed in your house
  • There is plenty of roof space ventilation

Factors To Consider When Sizing Ducted Air Conditioner

Here are some factors to consider when you size a ducted refrigerated air conditioning system:

  • How much shade does your property get? Are there trees around it?
  • If you already have ductwork, what is their existing condition?
  • What is the current insulation and ventilation state of your home?
  • The height of your ceiling
  • The number of occupants in your home
  • The type of material used in the construction of your home

Why Does Air Conditioning Size Matters?

The size of air conditioning matters A LOT because of one specific reason: Energy Efficiency. An air conditioner won’t function efficiently when installed in a too big or small space. For instance, you cannot expect a 3kW air conditioner to cool an entire home.

If you install an oversized air conditioner, you are setting yourself for many problems, such as:

  • Short cycling (the unit will turn on and off frequently)
  • An increase in energy bills
  • Increased humidity
  • Hot spots throughout the house due to inconsistent cooling
  • Wear and tear and shorter lifespan

If you install an undersized air conditioner, you can expect problems like:

  • The air conditioner will never stop running
  • Inconsistent temperatures throughout the house
  • The home will be never fully cooled
  • High energy bills
  • Excessive wear and tear will most likely lead to repairs or a breakdown

Choosing the wrong sized air conditioner might result in you bearing loss in the form of comfort, energy efficiency, and energy bills. Therefore, it is imperative to do some research and consult with professionals before purchasing a ducted air con.

Ducted Air Conditioner Installation Cost

Ducted air conditioning is no one-size-fits-all cooling solution. However, it is the most comprehensive climate control solution out there. Compared to a split system, the installation cost of a ducted air con is higher. Beyond the upfront cost of the unit, you’d have to take into account other expenses in the form of ductwork installation, drainage, electrical wiring, labour, or even the removal of an existing cooling system.

A fully supplied and installed 12.5kW ducted reverse cycle air conditioner would cost about $7000 – $9000 in Melbourne. Consult with an expert before buying ducted refrigerated air conditioning.

Read More: How Much Does It Cost To Run Ducted Air Conditioning.

Consult With Melbourne’s Air Conditioning Experts

Ducted air conditioning is no small investment, and that’s why it is crucial to choose the right size the first time. You can go with a DIY approach, but it could turn out to be a huge mistake. So instead, trust a professional to do the air conditioning sizing job for you. After all, that’s what they do for a living.

At ComfyHome, we have over 40+ years of invaluable experience in the AC industry. Our experts are more than capable of helping you find the right size ducted AC for your home and installing it. We offer a no-cost estimate to our clients in Melbourne. If you have any queries related to ducted air conditioning sizing, please feel free to Contact Us anytime.


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