10 Signs Your Ducted Air Conditioner Needs a Service

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10 Signs Your Ducted Air Conditioner Needs a Service


Ducted air conditioning is the ultimate climate control solution, allowing cool air to permeate through your home and keep you comfortable. You can control the temperature of individual areas (zones) in your home, from various control points such as wall-mounted units, smartphones, tablets, and laptops. Ducted air conditioners are also quiet, discreet, and efficient, potentially saving you money on your power bill, and adding value to your property.

But just like any electrical equipment, they need regular maintenance to keep them in top condition. Here are 10 signs your ducted air conditioner needs a service.

Why is a ducted air conditioning service important?

Ducted air conditioning systems are highly advanced pieces of equipment that require regular maintenance to keep them running at an optimal level. Regular servicing will ensure:

  • The life of your unit is extended, and it continues to run well over its lifetime.
  • Efficiency is optimised, and your unit can continue to maintain the desired temperature and remove moisture from the air.
  • Your unit doesn’t work too hard to achieve your desired heating or cooling level, which will keep energy costs down.
  • Dirt and debris in the unit are kept to a minimum, which will minimise pollution and its related health hazards.
  • Minor issues can be detected early, and costly repairs avoided.

How do I know if my system needs a service?

There are many issues that are common to all types of air conditioners, ducted or otherwise. However, due to their size and complexity, ducted air conditioners can exhibit a variety of unique issues you won’t find in other heating and cooling systems. These include:

1. Damaged ductwork

As the name suggests, ducting is the key to a ducted air conditioning unit. Ducts are constructed of different materials depending on the system, and in domestic units, they are typically made from rubber or bendable plastic.

Over time, tears and punctures can develop, or joins can come loose. These issues can lead to air escaping, which can decrease your system’s efficiency. In fact, up to 30% of your home’s heating or cooling costs can be wasted by leaking duct vents, because they need to run longer and more often to get results. 

Damaged ductwork can also compromise the lifespan of your system as small cracks and separations can create condensation on the outside of the ductwork, which can lead to corrosion. 

If ducts are located in an unconditioned area like a vented crawl space in the roof, damage can cause heated or cooled air to be forced out of unsealed joints, which then evaporates. Unconditioned air can also be drawn into the return ducts through the unsealed joints, which can exacerbate existing health issues. 

Damage to ducting can sometimes be patched, but if left for too long, it may need to be replaced—an expensive and unnecessary exercise that can be mitigated with a regular ducted air conditioning service.

2. Blocked ducts

Ducts can become blocked by vermin, including possums, rats and mice. Possums, in particular, often chew their way into the ductwork in search of shelter, particularly in winter. Ducts are the ideal pathways for them to roam around in and breed, and over time, the damage left behind can be extensive. Damaged ductwork can allow air to escape into the wall space and roof voids instead of being circulated inside the home, which leads to inefficiencies and an increased energy bill.

The faeces and urine deposits of these animals come with their own health concerns, but in addition, the air that leaves these infested ducts may also produce odours and become compromised, which will have a negative impact on efficiency as well as hygiene.

3. Dirty ducts

With most ducted air conditioning systems, dust and other airborne pollutants are pulled from inside the home into the intake or supply vents. The air is then heated or cooled, pushed through air vent diffusers that clean it, and the air is then redistributed.

If gaps are present in return air ducts, over time, the system can suck in elements like pollen, dander, mould, dirt, dust and other allergens, which can cause ductwork to become extremely dirty.

This can affect the indoor air quality of your home, and worsen health issues like asthma, nasal and eye allergies, and existing respiratory problems. If your home has pets, carpets or damp conditions, the level of allergens can be even higher and compromise the air quality even further.

4. Inadequate supply ducts

Well-designed duct systems distribute air efficiently throughout your home to keep all rooms at a comfortable temperature. Ultimately, the system should provide a balanced supply-and-return flow to maintain a neutral pressure within the house. If existing duct systems are inadequate or have design deficiencies in the return system, they will be harder to cool and heat.

Any rooms with a lack of sufficient return airflow will benefit from an upgrade by a professional air conditioning specialist. This can involve the installation of new return-air grilles, the installation of a jumper duct, or the undercutting of doors to allow for return airflow.

5. Insulation issues

Unlike split systems, where the distance between the outdoor and indoor units is relatively short, there is considerably more distance in ducted air conditioning units between the compressor and the air conditioning grilles. Longer distances essentially translate to the potential for more heated or cooled air to be lost. 

During hot weather and when your system is switched on, the cooling air prevailing around the ducts absorbs heat. During the winter, heat gets distributed via the ducting. However, if your insulation is damaged, decayed or ineffective, there will be a loss of energy, your system will operate less efficiently, and the unit will take longer to cool or heat your home.

6. Stuck or jammed zoning gates

Zoned ducted air conditioning systems have “gates” that allow you to control the airflow to your home’s individual rooms. If these fail, air may be directed to areas of the house you don’t want cooled or warmed. Maintenance requires a professional ducted air conditioning service, which may involve experts replacing broken gates, clearing clogs and jams, and/or fixing faulty actuators and wiring.

7. Dirty system coils

Condenser and evaporator coils are part of the outdoor elements of your ducted air conditioning unit, and over time, they can collect dirt and dust. And although filters can assist coils from rapidly soiling, they still need to be cleaned regularly to remove build-up. Dirty coils can reduce airflow and the ability of the coils to absorb heat, which can lead to overheating and a possible breakdown of the entire unit down the track.

8. Condensation drain issues

The condensation drain is located in the inside unit of your ducted air conditioning system. If not serviced regularly, it will prevent the ducts from reducing humidity, and will eventually overflow. This can lead to musty odours, negative pressure, blocked filters, and the dispersion of water throughout the outlets and main ducting, which can cause severe water damage to carpets, walls and furniture.

9. Clogged or dirty filters

This issue is not unique to ducted air conditioning systems — over time, debris and dust can affect any type of air conditioning and decrease its efficiency. It can also lead to a build-up of allergens in the filters, and each time you turn on the system, these are released into the air. This is particularly dangerous for people with low immunity, allergies, or those who suffer from respiratory illnesses like asthma.

During the warmer months, the risk of mould growth is also extremely high if filters are blocked. This is because the build-up of cold air combined with the outside temperature provides the optimal conditions for mould to flourish. Dust build-up can also cause coils and fan blades to corrode and/or rust.

Dealing with the issue in a ducted system requires a unique approach. This is because unlike split systems where filters are easily accessible, filters on ducted systems are located deeper in the ductwork. They are therefore more challenging to reach, and require the intervention of a specialist air conditioning team to rectify the issue during your regular ducted air conditioning service.

10. Electrical issues

If your ducted air conditioning system frequently shuts off for no reason, it could be due to the tripping of the circuit breaker that controls your home’s electricity supply. If you can’t restore power by flipping the circuit breaker back into the position, then it could be due to a fault that is causing the system to dangerously overheat. An experienced ducted air conditioning technician will be able to identify the issue, repair the unit, and ultimately keep you and your family safe.

When to arrange a professional service

Ducted systems are the most powerful air conditioning units on the market, and they are also the most complicated. This is mainly because much of the hardware of these systems is not easily visible. If there are issues with one component, it can also often have a domino effect and affect others, resulting in extensive damage.

Qualified air conditioning technicians will ensure your system is running at its optimal level. For ducted systems, it is recommended that you have a professional ducted air conditioning service performed every 12 months.

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