Your Ultimate Guide to Ducted Air Conditioner Zoning with A Senior Technician

By Jackson Sciano, Senior Technician

Air conditioning zoning technology has come a long way over the years, and these advancements have empowered consumers to have greater control over their air conditioning systems. In this article, we’ll explore the fundamentals of zoning, its benefits in terms of performance, efficiency improvement, as well as cost savings.


What Is a Zone?

A zone is a particular area of a home or building with individual climate control. If you have a refrigerated ducted system at home, chances are your bedrooms are classed as their own ‘zone’ as you can turn air flow off and on to those areas. The zone barrel itself is a sheet metal or plastic barrel with a blade in the middle, that can adjust on % based increments.

You can control these motors using touchpad or wall controllers, allowing you to open and close the blades within the barrel. This enables you to turn specific areas on or off, and in some cases, even control them with small incremental adjustments.


How Zoning Works

Zoning enables you to control the airflow to different areas of your home. It allows you to cool or heat only the areas you need, reducing the overall system’s capacity requirements and running costs. This approach is particularly useful for targeting high heat load areas when necessary.

In a typical home setup, you may have around five to seven zones, such as the living area, lounge, study, master bedroom, and remaining bedrooms. By turning off areas that don’t require conditioning, you can increase airflow to other zones, achieving your desired temperatures more efficiently.

However, it’s essential not to have too few zones on, as this can strain the system. In most cases, having a minimum of 2-3 zones is advisable, depending on the size and configuration of your air conditioning system. You can find more Etips on how to efficiently run your air conditioning in my previous blog post:


Your Ultimate Guide to Ducted Air Conditioner Zoning with A Senior Technician

Constant Outlets

Some older zoned ducted air conditioning systems have constant areas that are not zoned and only feature manual dampers. These outlets can either remain on whenever the system is running, or act as a spill area when not enough zones are selected by the user. They are typically located near the return air or above stairwells in multi-story buildings. Constant outlets help in circulating air back to the return air, ensuring better temperature control and efficient heating or cooling. They also act as a safety measure in case not enough zones are turned on during operation.

Percentage Control and Balancing

Modern zoning systems offer not only on/off functions but also the ability to control airflow volume using percentages. In the past, technicians had to manually adjust blades in the roof space to balance air distribution throughout the house. Air naturally flows towards the path of least resistance, so outlets closer to the indoor unit receive stronger airflow. This is where percentage control becomes crucial.

Setting Up Zoning with Percentages

Let’s explore some scenarios using percentage control to set up your zones:


Scenario 1 – Setup 1:

Kitchen: 80%

Lounge: 80%

Living: 70%

Study: 50%

Imagine your home as a puzzle with different pieces. The kitchen and lounge zones, totalling two outlets, face the North/West and have large windows. The living zone, comprising of three outlets, sits in the middle of the house, between the kitchen and lounge areas and the hallway where the return air is located. This zone not only cools the space but also aids in circulating air back to the hallway to achieve the desired temperature.

Now, the study zone, with just one outlet, is conveniently close to the indoor unit. It also has a small east-facing window. The airflow in this zone is naturally strong, so setting it at 50% is sufficient for its size. With this setup, we’re directing more airflow to the North/West areas with high heat loads, resulting in a consistent temperature throughout the house while maintaining good airflow.

Now, let’s imagine what happens if we modify this setup by setting the Living zone to 100%.

Scenario 1 – Setup 2:

Kitchen: 80%

Lounge: 80%

Living: 100%

Study: 50%

In this new scenario, we’ve redirected most of the airflow to the living zone, which is closer to the return air. While this helps achieve the desired temperature faster, it might make the kitchen and lounge zones warmer due to increased heat from the windows and decreased airflow.

Scenario 2

Here’s another situation we often encounter: the return air is located at the back of the house, where bedrooms 2, 3, and 4 are situated. However, the client primarily uses the front and middle sections of the house. The system is set to cool the house to 24 degrees. By the time the system stops cooling, the living area reaches 21 degrees, while the hallway with the return air is at 24 degrees. This can be attributed to the absence of a constant outlet, a situation becoming more common with percentage control systems and every outlet being zoned.

To address this problem, we can enhance the previous zoning setup with one additional element.

Scenario 2 – setup 1:

Kitchen: 75%

Lounge: 75%

Living: 70%

Study: 50%

Bedroom 2: 30%

Imagine the same house, but it’s now a longer-scale version of the previous one. The nearest living outlet is about 8 meters away from the return air. Bedroom 2, though unoccupied, plays a crucial role in the system’s operation. As mentioned earlier, there’s a significant temperature difference between the living area and the return air in the hallway. So, we slightly open bedroom 2’s outlet and keep the doors to bedrooms 3 and 4 closed. By doing this, bedroom 2 acts as a constant outlet, aiding in maintaining the desired temperature and airflow back to the return air. This adjustment reduces run time, energy costs, and equipment wear, providing more accurate temperature control throughout the house.

Your Ultimate Guide to Ducted Air Conditioner Zoning with A Senior Technician

In Conclusion

Proper zoning and airflow balance is essential for optimal system performance. There are various zoning setups available, and a “set and forget” approach won’t yield the best results. It’s important to note that improper usage of zoning can have the opposite effect, negatively impacting performance, increasing operational costs, and potentially shortening the lifespan of equipment. Each zone, when using percentage control, may require different settings to achieve peak performance, whether through minor or significant adjustments.