Ducted Air Conditioning – What it is, and how it works

South Australia is the driest state in the driest country in the world, with a reputation for breathtaking heat in the summer months. In fact, the deadliest natural disaster in Australia’s history (the 2009 heatwave) claimed over 50 South Australian lives. As such, we take our aircon pretty seriously, and ducted air conditioning is a pretty common sight in South Australian homes.

But how does ducted air conditioning work, exactly? How is it different from the split systems you might see mounted on a wall? What different types are there? And what do I need to know about having a ducted system in my home?

Let’s dip into the world of ducted air con for a little while, and answer some of the questions you might have about this awesome piece of household technology.

Key Takeaways:

• Ducted air conditioning is aircon installed in the roofspace of a home or property that blows cool air into the house through ducts and air vents in the ceiling.
• Ducted air can simply cool an entire house, but is commonly “zoned”, allowing the cooling (or heating) to be turned on and off in different sections of the house. Many modern units even let you set different temperatures for different rooms.
• Ducted aircon can be reverse cycle, or evaporative. Evaporative cools very efficiently, but can’t heat. Reverse Cycle is more versatile, and can heat as well as cool. Split systems are also reverse cycle, but only cool one or two rooms.
• Evaporative air draws air into the house, cools it with added water, and blows it through the house and out the windows. It’s less effective when the air is already humid.
• Reverse cycle takes the air already in the house and cools it down, blowing it through coils of chilled liquid.
• Ducted generally starts at around $8000 – $12,000 to install, and can go a lot higher for larger units or more features
• It’s hard to estimate the cost of running ducted aircon, as it’s affected by many factors. But an average Adelaide household might spend $900 on cooling, and the same on heating. Evaporative costs FAR less to cool, but can’t heat — meaning more expensive heating is normally needed. Reverse Cycle heating is quite efficient compared to other types of heating.
• Maintaining your ducted aircon can keep it working efficiently and lengthen its lifespan. This might involve getting up on the roof in some cases.
• Ducted aircon should be professionally serviced around once a year. Spring is an excellent time for this, meaning your aircon will be working at its best in summer.
• A well maintained Ducted air conditioner can last 20–25 years.

What is ducted air conditioning?

Ducted air conditioning is air con that blows cool air into your house through a series of air ducts, normally located in the roof. These ducts connect from a cooling unit in your roofspace (the space between the ceiling and the outer roof of your house) to vents in your ceiling. Normally, the only visible sign of ducted air conditioning inside your house will be the ceiling vents, and a small touchpad control panel in one or more rooms.

Ducted air conditioning is often regarded as the gold standard for home air con, as it’s able to cool many rooms at once — sometimes even the whole house. Most modern units are also designed so the cooling can be turned on and off in specific areas, or even set to different temperatures in each room.

Are there different types of ducted air conditioning?

Yes. The two common types of ducted air conditioning system used nowadays are conventional air conditioning (which are normally “reverse cycle” systems), and evaporative cooling. These are quite different technologies, and although they’re both installed in the roofspace and use ducts to blow air into the house, that’s about where the similarity stops. They work in very different ways.

So for example, evaporative cooling requires open windows and doors to work correctly, while conventional AC is far less effective if the windows are open. And evaporative systems can’t be used for heating. We’ll look at why that’s the case shortly.

How ducted air conditioning works

The idea of ducted air conditioning is to cool multiple different rooms and spaces in your house from a single cooling unit installed in the roofspace. The air is pushed through each duct and out of the ceiling vents to cool the rooms below.

The “ducts” are normally flexible, lightweight tubes a little wider than a basketball, and made of silvery, foil-like material. This makes them very lightweight, easy to position, and tougher than you might expect.

In older ducted air conditioning, the airflow was either on or off — so to cool any room in the system, you needed to cool every room. However, most modern ducted air conditioning now features zoned air conditioning.

In a zoned aircon system, each junction in the air ducts (where one duct splits off into several) is fitted with tiny motorised hatches inside the duct that can open and close to block airflow or allow it through. These are wired up to the air conditioner’s controls and set-up to be opened and closed in specific groups — called “zones”.

So when someone activates a certain zone on their touchpad, this allows the air through the ducts that lead to a specific area of the house, cooling that area.

To give an example, let’s say a house had five aircon zones — three bedrooms, a kitchen/dining room, and a lounge room. If someone turned on their zoned aircon and turned on the “Bedroom 1” zone and the “Kitchen / Dining” zones, the controller would set all the hatches in the air ducts so those leading to the main bedroom and the kitchen/dining room were open, and the rest were closed. Which means those two spaces get cooled, and the others don’t.

Many modern aircon units take this even further, with hatches that can be partly opened, changing the amount of air allowed through. This means that different rooms can receive different amounts of cool air, allowing you to set each zone to a different temperature.

That’s how the ducts work. As for how the aircon unit cools the air, and where the air comes from and goes, that depends on what kind of ducted aircon you’re using. So let’s take a moment to look at each type.

How does Conventional Air Conditioning work?

Conventional air conditioning is the most common type of air conditioning technology used nowadays, and uses the same principles as a refrigerator. Basically, the air conditioner has a chemical known as refrigerant that loops around inside the system, carrying heat outside your house. First, the chemical is cooled to a very low temperature (using some clever physics) and then pushed through metal coils inside your aircon unit. Fans blow from your house through these coils, cooling the air down and transferring some of that heat into the refrigerant.

The cool air is then blown into your house to cool it down, while the cold refrigerant — which has now become a cool gas — is sent outside the house. There it’s converted into a very hot, high-pressure gas (again with clever physics). Here it once again travels through metal coils and has air blown through it — although at this point, this cools the liquid down and blows the heat out of the house as hot air. You may have noticed that the vent on the air conditioning unit outside your house is not a nice place to stand in hot weather.

This cools the coolant down and turns it into a warm liquid (still at high pressure), at which point it’s physics-ed back into low pressure cold liquid and sent back inside the house to start the cycle again.

This means conventional air conditioning always has four main components.

• The Evaporator — Cools the air by blowing it through coils filled with cold refrigerant.
• The Compressor — Turns the now cool refrigerant gas into pressurised hot gas.
• The Condenser — Blows outside air through the refrigerant again, cooling it down and blowing the heat away as hot air.
• The Expansion Valve — Turns the pressurised, warm refrigerant into a cold low-pressure liquid, and starts the cycle again.

If you want to know more, you can check out a more detailed explanation on our Split System Guide. And there’s also a pretty good explanation on the How Stuff Works website.

In a conventional ducted system, the air is drawn from the house into the cooler through a central vent called a “return air”. It’s blown through the evaporator to cool it down, directed out through the ducts to different rooms, and is then blown down into the living spaces through the roof ducts.

The cool air then passes through the house, and is eventually drawn back into the return air to continue the process. You may notice that with a conventional air conditioner, the vents are normally placed near the outer walls and far from the door. This is so that the cool air from the ducts passes through as much of the house as possible before getting drawn back into the return air.

How does a Reverse Cycle Air Conditioner Work?

A reverse cycle air conditioner uses exactly the same process described above, but with one key improvement — it’s reversible. When needed, a reverse cycle aircon can reverse the direction of the coolant travelling through the system, so the Evaporator and the Condenser switch jobs. That means that the system is now blowing warm air inside the house and cold air outside — meaning it heats your house rather than cooling it.

This is obviously very useful in cold weather, which is why most modern conventional air conditioners are reverse cycle.

How does Evaporative Air Conditioning work?

Evaporative coolers — known in some countries as “swamp coolers” — work very differently to conventional air conditioning. So if you’re staying in a house with ducted AC, it’s important to work out what type of aircon it is. The basic idea behind evaporative cooling — that wet things get cold when you blow on them — has been around for a very long time, and was used in Ancient Egypt to cool people down. In fact, it’s the same method your body uses to cool itself. When you’re sweating in the heat, and you feel a breeze drying up the sweat and cooling you down, that’s evaporative cooling at work.

In an evaporative cooler, dry air is sucked into the cooling unit (normally located on your roof) and pulled through a wet fibrous pad, a little like a sponge. The air absorbs water from the pad, which cools it down and makes it more humid. This cool, humid air is blown into your house, which then pushes the warm air that was in your house out open windows — which is why you need the windows open with evaporative AC. This process continues, giving you a constant flow of cool air flowing in through the ducts and out the windows.

How does evaporation cool things down?

The way it cools things makes use of something called “latent” heat — which is stored heat energy that you can’t actually feel.

When water changes into vapour, the water molecules absorb enough heat energy to break free of the liquid water and float freely as vapour. This heat is actually stored inside the molecule as latent heat. That means the heat energy is still there, but you can’t actually feel it — the word “latent” actually means “hidden”.

This means that as the dry air passes through the pad, some of the heat from the air is absorbed by the water molecules and locked inside them — keeping the molecule in vapour form. This means the air gets colder. The actual amount of heat energy in the air is the same, but some of the heat is locked inside water molecules as latent heat, so it feels colder overall (you can’t feel latent heat).

Have you ever seen those water absorbent gel balls used in gel blaster toys? They start off as tiny beads, the size of rice bubbles. But if you pour them in a bowl of water, when you come back later the water is gone and the bowl is filled with clear gel balls the size of marbles. The water is still in the bowl, but it’s been absorbed by the gel balls. So if you put your hand in the bowl, it won’t get wet.

Similar idea with evaporative cooling. You add water molecules to warm air that absorb the heat and lock it away. The amount of heat in the air hasn’t changed, but you don’t feel it because it’s been soaked up and converted to latent heat. So the “sensible heat” of the air (the temperature you feel) is cooler.

This also explains why evaporative cooling doesn’t work well in humid weather — and why it’s hard for people to stay cool if the humidity is too high. Air can only absorb a certain amount of water vapour, so humid air can’t absorb as much water as dry air. If the air blowing through the wet pad in the cooler is already full of water molecules, it’s going to absorb much less water from the pad — so it won’t cool the air as effectively. Likewise, humid air blowing over your face won’t cool you down as much as dry air.

If you’re hoping for more information than that, there’s another decent explanation over at HowStuffWorks.com.

How is ducted AC different from split system air conditioning?

The answer most people are looking for when they ask that question is that ducted is normally mounted in the roofspace, provides air to multiple rooms through vents in the ceiling, and can either be evaporative or reverse cycle. Split systems normally have a large plastic box mounted on the wall above head height, are always reverse cycle, and generally only cool one room or space.

That’s the simple answer to the question.

In reality, it’s a little more complicated than that because many ducted systems are also split systems.

The less simple, more accurate answer is that “Split System” is a term for a conventional air conditioner which is split into two parts — the evaporator in one part, and the compressor, condenser, and expansion valve in the other. The part with the noisy compressor and the condenser blowing out hot air goes outside the building (on the roof, or an outer wall), while the Evaporator is inside where it can cool the air without making too much noise. The two are connected by thin, insulated copper pipes which carry the coolant between the two parts — generally through the walls or the roofspace.

There are a range of different types of split system. But in Australia, if you’re talking about “split system aircon” for a house or business, you’re generally talking about a high wall split system — the type with the large plastic box mounted on the wall, and a small remote control to turn it on and off.

“Ducted” just means the unit is (usually) mounted in the roofspace, and uses air ducts to direct cool air into the different rooms. We use that same term to talk about conventional or reverse cycle air conditioning, and evaporative coolers. So if you’re told a house has ducted air conditioning, it could be either type.

Could I have both ducted and a split system AC?

Yes, you can have both in your house, although you shouldn’t use them together.

Broadly speaking, this normally refers to having ducted evaporative in the roof, and one or more split systems in specific rooms. It makes little sense to have ducted reverse cycle aircon AND a split system (they do the same job), and there’s no such thing as an evaporative split system. This allows you to cool your house more affordably, but still take advantage of the versatility of reverse cycle air at other times.

There’s nothing wrong with this if you’re willing to pay the extra cost to install both systems. But it’s important to remember not to run both systems at the same time! This might seem like a way to cool the house down quicker, but the two types of air conditioner work so differently that they actually stop each other working effectively.

An evaporative cooler blows air through your house and out the windows. Warm air is drawn in through the cooler and cooled down with water (adding water vapour in the process). It’s then blown into the house through the ducts, and out the windows — taking the water vapour with it. So there’s a constant flow of air, and you need some windows open for the system to work.

A reverse cycle air conditioner uses the air that’s already in the house, drawing it in from the room and cooling it down in the evaporator before blowing it back into your space. It works best with the windows closed. It also dries the air, as the water vapour in the air condenses into liquid as it passes through the Evaporator coils, and gets left behind.

So if you run both at once, the air cooled by your split system is mostly wasted, as it gets blown straight out the window. Also, because the evaporative cooler is constantly adding water vapour to the air, more and more moisture will be passing through the Evaporator coils and turning back to liquid — meaning things are going to get very wet very quickly around your split system unit.

As such, if you have both, make sure you’re only using one at a time.

What are the advantages of ducted air conditioning?

If someone is building a house in Australia and aiming for luxury, they’ll normally install some form of ducted air conditioning. Even the most basic units without any zoning ability have the advantage that they cool your entire space — not just one or two rooms. So at the end of a long summer day, your whole family can relax in the cool without needing to all stay in one specific room.

With most modern AC, you also get the advantage of zoned cooling — you can set which areas of the house are cooled (or heated, in the case of reverse cycle AC). This allows you to be more efficient, only using the electricity needed to cool certain rooms. More advanced systems or controllers (like the AirTouch 5) even allow you to set different temperatures in each room (to allow for different comfort levels), set the temperature with your phone or smart assistant, or even set it to detect when you’re driving home and turn on automatically.

Broadly speaking, some of the advantages of ducted air conditioning are:

• Cools the whole house — Ducted allows you to control the temperature in multiple rooms all from the one controller.
• Cheaper for multiple rooms — Although split systems are more efficient for a single area, ducted is far more efficient as soon as you’re trying to cool more than 2–3 rooms.
• Looks better — Generally the only sign of ducted aircon inside the house are small air vents set into the ceiling, and a controller on the wall.
• Quiet — Most modern air conditioners are quiet, but because the aircon unit is up in the roofspace and away from you, many ducted systems are quiet enough that it’s hard to know if they’re on without looking at the controller.
• Property Value — Having ducted air conditioning will add to the appeal of your house if you choose to sell.
• Lasts longer — If you look after it, a good quality ducted aircon unit can last you two decades or more — twice as long as the average split system.

Are there any downsides of ducted air conditioning?

There are a few reasons why ducted AC might not be the ideal choice for your situation.

First, getting ducted is more expensive than a split system — normally around 2–3 times the cost. Secondly, ducted is less efficient at cooling just one or two rooms than it is at cooling a whole house. So if you only have one or two spaces to cool — such as the bedroom or lounge room — ducted aircon may be overkill.

You can think of it a little like selecting a car. If you only drive short distances around town, and you use public transport a lot, then a big station wagon with a larger engine is probably not ideal — it’s a little less fuel efficient, and probably harder to park. So a zippy little two-door car is possibly all you need in that situation. But if you spend a lot of time driving — particularly travelling long distances on the highway — then you’re probably going to want the big, comfortable car with cruise control and good mileage on the open road.

Same deal here. If you only need to cool one or two frequently used rooms, you can probably get by fine with just a split system.

In addition to this, ducted air conditioning needs a roofspace or similar space to put the cooling unit. So houses that don’t have much useful roofspace — such as multi-story apartments, or multi-story houses not built with air conditioning in mind — may not be able to install ducted air con as there’s simply no-where for the ducts or the air con to go.

Should I go reverse cycle or evaporative?

This very much depends on your situation and your needs. The two types of air con have distinct strengths and weaknesses, and you need to choose which factors are more important for you. To summarise some of the differences…

The key trade-off here is that Evaporative cooling is a lot more energy efficient for cooling, but it can’t be used for heating, and it’s far less effective if the weather is humid or very hot. Reverse cycle air conditioning is a little more expensive to set up and run for cooling, but it’s far more versatile — and it actually offers pretty good efficiency for heating.

So the question is, are you looking for cheap cooling, or all-round versatility?

If you’re looking for more information, Canstar blue has some useful pages on the difference between the two.

Should I run ducted air con to every room?

Not necessarily. Although one of the advantages of ducted is having cooling throughout the house and being able to cool down the areas you choose, there are often spaces in your house that don’t really need aircon — such as indoor carports and storage areas.

If you’re looking at getting aircon installed, this is generally the sort of question that a consultant can help with. A good aircon quote will be designed for your specific house layout, placing ducts and vents where they’ll do the most good.

Are there limits on where I can install ducted air con?

The main consideration is the roofspace — does the property have the physical space to install the inside aircon unit and the air ducts needed?

You also need an outside area where the external portion of the air conditioner can be installed. This normally needs to be on the roof for evaporative, but could be a roof or outside wall mounting for a reverse cycle system — which means you normally have a few more options when installing reverse cycle.

It’s also worth noting that while ducted aircon is definitely an option for two-story homes, this is normally more an option when building a new home — it’s a lot more complicated to fit ducted aircon to a two-story building if the people building it weren’t planning for air ducts in the design.

What sizes/types of ducted air con can you get?

This depends on the type of air conditioner, as they use different measurements.

Reverse Cycle

Reverse Cycle air conditioners are rated in kilowatts (kW), and most household units range from around 7kW up to around 25kW. There are sizes larger than that, but they’re normally used for things like businesses and schools, and you won’t normally see them in residential homes.

It’s worth knowing that once you’re going about 18kW level, you’re looking at a fairly heavy duty aircon unit that will probably need three-phase power to run. If you have no idea what that is, all you need to know is that it’s a type of electrical wiring used in large properties that can provide a lot more power than the normal “Single Phase” wiring used in most houses. But it’s not standard in residential properties — it costs more, you’ll normally only find it at business and very large houses. So if you’re hoping to get an XXL air conditioner, there might be a hidden cost required — upgrading your home’s electrical setup.

If you want more detail than that, there’s a pretty good explanation of what three-phase power is all about over at TheConversation.com.

As a rule though, most houses aren’t going to need anything that large.

Evaporative

Evaporative aircon is measured a little differently, being normally rated by the amount of air they can push through every second. This will be normally measured in litres per second, or cubic meters per second. For reference, 1 cubic meter per second (m³/s) = 1000 litres per second (l/s) — which makes the maths nice and simple.

In some cases, the rating might be given in CFM, or cubic feet per minute. That sounds confusing to convert, but in reality, 1 Lt/S = just under 2.2 CFM. So for any numbers given in CFM, you can just halve the number to give you a rough estimate — or just use an online converter.

What type of system would I need for my space?

Here’s a rough idea of what sizes of aircon are suitable for what types of space.

Example sizes for ducted reverse cycle air conditioning:

For evaporative, the general rule is that your system should be capable of pushing through the volume of air in the rooms you want cooled every two minutes.

So for example, let’s say you want to cool four 4m × 6m rooms with a ceiling height of 2.4m. Each room will have a volume of:

4 × 6 × 2.4 = 57.6m³

Four of those will be 230.4m³ total volume, or 230,400 litres.

To push 230,400 lt of air in two minutes, you’d need to move air at a rate of:

230,400 ÷ 120 seconds = 1,920 l/s

So you’d want an evaporative unit rated at 2000 l/s, (or 2 m³/s, or 4250 CFM) or better to cool a space that size.

Realistically, those are just rough ballpark estimates. There’s a lot of things to take into account when installing ducted aircon. So while doing your homework is smart, you’re going to want to get quotes from companies who’ve inspected your home and know all the factors to consider.

Is it important what brand I choose, or are they all basically the same?

No, not all conditioners are equal, and the brand can make a big difference. As a general rule, air conditioning is one of those areas where you get what you pay for — so going for a budget air conditioner isn’t normally the best strategy for something that’s going to be in the roof cooling your house for the next decade or two. But it’s not just as simple as “more money means better”.

When you’re comparing brands and models of air conditioner, it’s important to pay attention to the sort of warranty and after-market service the company offers. Generally, companies won’t offer a long warranty and good service on poor product, so this can be a good indication of how reliable the unit is likely to be.

It’s also a good idea to check out independent review sites like Canstar Blue, as they can give you a good sense of how different brands compare, and if any are unusually good value for money.

How much does it cost to run ducted air conditioning per hour?

That’s a… really tricky question, because it depends on a lot of factors.

Just looking at ducted reverse cycle, as a ballpark figure, Canstar Blue estimates that cooling your house with ducted reverse cycle air conditioning will probably cost you between $384 and $1,964 a year for cooling, and between $97 and $1,457 a year for heating. Now if you’re thinking that’s a very broad price-range, and it still doesn’t give you an hourly figure, you’re right.

So here’s why it’s tricky. The cost of your air conditioning is dictated by two things — the cost of electricity, and how much electricity the aircon is using. Where it gets tricky is that the amount of electricity the system uses will depend on how much work it has to do to cool the space — i.e. how much heat energy it’s having to move outside your house each hour. And there are a lot of things that affect that. Just to name a few:

• The current temperature inside the house (i.e. how much work does in need to do when turning on to get the temperature where you want it)
• The temperature outside (on a hot day, your house will be constantly absorbing heat from outside)
• How well insulated your house is (good insulation means the house absorbs the outside heat more slowly)
• Whether you have doors or windows open
• Whether blinds and shutters on your windows are down
• How much space you’re trying to cool — how many rooms, what floor area, etc.
• How high your ceilings are (rooms with higher ceilings have more air to cool, and can trap heat up near the ceiling)
• The layout and location of your home (does it get lots of direct sunlight, or cool breezes off the ocean, etc)
• The temperature you set your thermostat to (cooling a house to 17°C uses a lot more energy that cooling it to 22°C)
• How energy efficient your aircon unit is
• How well maintained your aircon is (poorly maintained units aren’t as efficient)
• How many people are in the house (people generate a surprising amount of heat!).

These are some of the factors that affect your hourly energy consumption rate. Your overall annual energy consumption is also affected by things like:

• How much of the day you run the aircon for
• What times of day you use it
• The climate where you live (hot, cold, humid, dry, etc)
• Whether you have solar power (to offset the energy usage)
• Whether you have other ways to heat and cool (like gas heating, or ceiling fans)

For that reason, it’s really hard to give any sort of reliable numbers on the cost of running aircon in a given household — there’s just too many variables in play.

However, to give a very general idea of the sorts of costs involved, the following info shows some average costs for running ducted aircon in different Australian cities.

Source: Canstar Blue

Isn’t evaporative air conditioning a lot cheaper than reverse cycle?

Actually, it’s a little more complicated than that.

If you put the two side by side, both running throughout the day on a bright, clear 30°C day with low humidity, then yes — evaporative aircon is streets ahead of reverse cycle, using less than 20% of the electricity of conventional air conditioning, so they’re definitely more efficient.

Where it gets complicated is when you start to compare energy costs over the entire year, including heating. Because while evaporative is cheaper to run, it doesn’t cool — meaning you’ll normally need an alternative in colder months, which can be far more expensive. Whereas by contrast, heating your home with reverse cycle air conditioning (also sometimes known as a heat pump) is very efficient compared to the alternatives, like gas heating and electric fan heaters (which are notoriously greedy for electricity).

As a matter of fact, reverse cycle aircon is potentially one of the cheapest types of heating on the market.

Also, the rising popularity of solar panels is making electric heating (including reverse cycle air) a far more affordable choice, as the sun provides much of the power needed — which is not true of gas or wood-fire heating.

So broadly speaking, once heating is included in the mix, reverse cycle air doesn’t do too badly in terms of running cost.

How much does ducted air conditioning cost?

The cost of installing a ducted air conditioner can vary massively, depending on what you’re installing. Broadly speaking, ducted aircon starts at about $8000 – $12,000 and can range well up into the $20,000 – $30,000 range depending on the size and brand of the unit and the different features you include. Evaporative coolers tend to be cheaper to install, but again — this depends on many factors.

Realistically, when you’re trying to price-up the cost of installing ducted AC, there’s no substitute for doing the homework. Look up air conditioning installers that service your area, preferably with good reputations — not all aircon companies are the same. Get recommendations from friends. Ring around, and get quotes, inspections, and numbers, and pick the option that best suits your situation. It’s a big decision, so take your time and make the right choice.

A few things to bear in mind, though:

• Don’t go for the cheapest option — It’s a big investment, so don’t choose a budget brand.
• Remember to factor in the installation cost — Don’t just assume an ad for a $7999 air conditioner means that’s all you’re paying.
• Always get an inspection for a quote if you can — You’d be surprised how many quotes fall short because something in your house wasn’t quite as expected.

If you’d like help to get started, REQ does free, no obligation inspections and quotes for aircon installation throughout South Australia. We’re also happy to answer any questions you have, obligation free! Give us a call (1800 202 073) or visit our website to get started — we’d love to hear from you!

If I upgrade my ducted aircon, can I switch what type it is?

When you’re switching out your ducted air conditioner with a new unit, it will involve removing the previous unit as part of the process. So yes, you can definitely switch from evaporative to reverse cycle or vice versa. However, it is a little more involved than just switching one cooler unit for another.

A normal question people ask when making such a switch is “can we just use the same ducts and vents?”. And the answer to that is, “No, you shouldn’t”. Some companies might be willing to do it to cut corners on the cost, but it’ll mean your aircon doesn’t work as well. The reason for this is the location of the vents.

As mentioned before, evaporative coolers blow air into the house, and out the windows. This means that the ideal placement for evaporative vents is away from the windows and towards the centre of the house, so the cool air will travel through as much of the house as possible on its way out the window.

Reverse Cycle is the opposite. The air it blows into the house travels back to the return air — a larger ventilator somewhere near the centre of the house. So the vents for reverse cycle need to be near the outer walls so the cool air travels right through the room on its way back to the return air.

So if you use vents from one type of aircon with a different type, then the air will be going the wrong direction and won’t cool most of the room. Reverse cycle air from evaporative vents will go straight out the window, and evaporative air from reverse cycle vents will go right out the door and back to the return air.

Generally, when you’re switching the type of ducted aircon you have in your house, it’s better to think in terms of replacing your aircon rather than upgrading it.

Can I run ducted air con all day?

Yes. Modern Australian aircon units are designed to run for days on end when required — it’s par for the course in a country where temperatures over 40°C are not uncommon. It can be expensive, but it’s often worth the cost — and sometimes even life-saving.

To avoid heatwaves getting too expensive, it’s worth making sure you’re taking other steps to keep your house at a comfortable temperature — drawing curtains and blinds to limit sunlight, and keeping doors and windows closed where possible. Also, it’s important to choose your aircon temperature carefully. The further you set the thermostat from the temperature of the air outside, the more expensive it will be.

Do I need to do anything to maintain my ducted aircon?

To keep reverse cycle aircon working smoothly and efficiently, you should clean the filter in your return air every few months (at least twice a year). This can be removed and washed outside using a garden hose. Don’t vacuum the filter (as this can damage it), but you can vacuum the grille itself.

The process can be slightly different from unit to unit, but generally, you’ll be able to find information on how to do this in the manual for your unit, or on the manufacturer’s website. There are also many useful how-to videos on YouTube, such as this one from AirTouch.

You should also check the external unit of the air conditioner every few months and ensure the grilles aren’t clogged by debris or leaf litter — it can’t cool your house if it can’t blow the hot air out.

With evaporative coolers, it’s a good idea to remove the filter pads on the unit every few months and wash them off — again with a garden hose. It can also be helpful to flush the water tank to get rid of sediment or dirt in the water, and make sure the fan and its housing are free from debris. Again, you can find useful information on what to do in the manual, on the manufacturer’s website, or on YouTube.

Because doing maintenance on an evaporative cooler generally involves getting up on the roof, it’s not uncommon for people to leave the job to professionals. But if you’re willing to get on a ladder and do some simple maintenance, you can keep your evaporative working longer and performing better.

How often does ducted air conditioning need to be serviced?

To keep your ducted AC working smoothly (and costing less), it’s worth getting it professionally serviced every 12 months or so. It’s a good idea to get into the habit of having your unit serviced in late spring or autumn, just before the extreme weather hits and you want it working at its best.

Spring is best for evaporative coolers, which normally don’t see much use in winter.

Generally, having a ducted aircon unit serviced will cost you between $200-$400, depending on the company.

If you’re looking to get your aircon serviced in the near future, REQ services ducted AC for $264, anywhere in the greater Adelaide area. We’d love to hear from you!

How long will a ducted AC unit last?

If maintained well, a good quality ducted air conditioning unit can last up to 20–25 years — making it a significant investment in your home. This is one of many reasons why it’s worth carefully shopping around when considering ducted aircon, and making sure you’re getting a reliable brand from a trustworthy installer. Do the homework, get inspections and quotes, and take your time.

Conclusion

Ducted air conditioning is very much the gold standard for aircon in Australian homes. With two main types and a large range of options for control and temperature zoning, it can be anything from a one-button way to cool an entire house to a highly sophisticated climate control system that can set temperatures room by room from your home assistant.

Getting ducted AC for your home doesn’t come cheap, and it’s not suited to every household or situation. But good quality, well maintained ducted air can keep your house and family comfortable for an entire generation. It’s an investment in your home that not only makes life more comfortable, but increases the value of your property. So it’s worth investing some time and money into getting it, and some effort into keeping it in good condition.

The information in this blog has been checked and verified by…

Filip Krawiec
CEO of REQ Refrigeration & Air Conditioning

The information in this article was reviewed and checked for accuracy by Filip, who also provided much of the source information.

Filip is the owner and CEO of REQ. In addition to owning and running his own air conditioning business, he’s also a fully qualified and highly experienced air conditioner technician. He’s worked in the AC industry for more than a decade — repairing, installing and designing builds for all types of AC systems. He’s also appeared on podcasts as a local expert in the air conditioning field.

Braydon Fleming
Install Manager at REQ Refrigeration & Air Conditioning

The information has also been reviewed and checked for accuracy by Braydon.

Braydon is the install manager at REQ, responsible for overseeing the installation teams and ensuring all work is done to a high standard. Braydon has four years of tertiary qualifications in the mechanics of air conditioning, and nearly a decade working in the field — as a technician, managing teams of other technicians, and training apprentices in the trade.

Article written by…

Lochy Cupit
Content Writer, Author, Storyteller, and Wordsmith

Lochy Cupit is a professional content writer, content researcher, published author, multimedia & web developer, youth worker, actor, radio presenter, podcaster, and creative arts specialist. He holds bachelor’s degrees in computer science and multimedia, a masters in creative writing, and a graduate diploma in theology – because “why study just one thing”? He lives in Adelaide with his wife and two highly energetic boys.