Air conditioner frequently asked questions


Do you have any air conditioning tips?

Thermostats should be set at 23°C. Every 1°C lower (on cooling) or (higher on heating) can increase running costs by up to 15%.

If there is a hot day forecast, then pre-cool your house the night before. This is especially effective if your house has a high thermal mass such as solid brick. This will allow your air conditioner to work at its optimum during the cool evening, saving power and wear and tear on the unit. It also allows the unit to keep on top of the heat load as it begins to warm up during the heat of the day.

What are my expected running costs?

Power kilowatts are different to heating and cooling kilowatts. The first one deals with actual power consumption while the other deals with capacity. A unit drawing 746W (1Hp) of electricity may move 2 to 3.5 times that in ‘capacity’. That is to say, it’s ability to add or remove heat cooling or heating your premises
Systems are judged on their efficiency by their Coefficient Of Performance (COP) in the case of heating, or the Energy Efficiency Ratio (EER) for cooling. The EER and COP are calculated by dividing the capacity output divided by the electrical input. An interactive side-to-side comparison of air conditioners, showing energy efficiency ratings, power consumption and estimated running costs can be found here
Single phase (240v) systems are available in ducted splits up to 18kW and non ducted splits up to ~14.5kW. Systems larger than this would require three phase power (415v). If you don’t have it, you’d need to run new mains, replace the meter and rewire the main switchboard. This would be in the vicinity of $1500–$2000 as a rough guide. More if existing boards etc. need to be replaced.

How about old R22 refrigerant run systems?

Older hydrochlorofluorocarbon (HCFC) based refrigerants are in the process of being phased out due to their ozone depleting potential (ODP). That means the current air conditioning refrigerant R22 has a limited life span. That means the cost and downtime of repairing R22 based systems is becoming far less economical then replacing them with brand new 5 year warranty systems that are fully inverted and run on much more efficient refrigerants such as R32 or R410a which have an ODP of zero.

What is the difference between inverter and non-inverter?

The difference between inverter and non inverter is the inverter units can alter their speed in response to the cooling or heating demand. Nearly all systems both wall split and ducted are fully inverted with only the very chap ones having a inverted start up only. Inverted systems only use the minimum amount of power consumption to achieve your desired temperatures as opposed to DOL (direct on line) which continually uses the maximum amount of power whenever the system is in use. Inverter systems are quieter, much more energy efficient (around 25%) and save wear and teat on your system componentry.

Can I get Legionnaires Disease from my domestic air conditioner?

Legionnaires disease has been overblown by the media and it is not something you can contract from domestic air conditioning. The majority of cases are caused by incorrect cooling tower maintenance. Cooling towers are primarily used in commercial air conditioning to cool water cooled condensers and industry to cool recirculated water. They provide an ideal place for Legionella bacteria to grow (temps between 28 to 40°C) and the operation of the towers causes drift which aerosols the bacteria allowing people to breathe it in. There’s probably more danger handling potting mix than from a cooling tower because by law all towers have to be maintained and treated with biocide. Evaporative coolers have been suggested but not verified as potential disease transmitters. Modern evaporative coolers also have dump valves which further lessen the risk.

What are the best brands?

The old adage ‘You get what you pay for’ exists for a reason. The dearer units such Daikin, Mitsubishi, Fujitsu are generally more efficient and quieter. They also go together better and give you a better finished product. This translates to easier servicing should the need arise which in our opinion makes the additional purchase costs worth considering. However, some of the cheaper brands provide excellent value for money and offer very good performance. Final decisions should be based on specific unit performance and value for money. There is very little difference between the mainstream and top units sold these days. It’s only in the very cheap units that quality begins to suffer.

What sort of maintenance is involved?

• Evaporative coolers: the newer ones self drain but they still need flushing and sanitizing. Annually for domestic and bi-annually for commercial. The integrity of the system also requires to be tested for correct water level, float operation, cooler pump and fan motor performance.
• Air Conditioners: the return air filters require cleaning. Wall split systems particularly require a full strip down and pressure clean in order to maintain their energy efficiency and for the removal of bacteria and mould spores that in some cases can cause critical health issues. Ducted and package systems also require filters and drains to be maintained as well as full integrity test to ensure the system is kept running at peak performance.
Please remember, air-conditioners become more expensive to run when not properly maintained

What makes a quality installation?

All installations are not equal – Most refrigerated systems fail due to poor installation practice not defective units. A good way to protect yourself is to use a knowledgeable refrigeration technician. Ask questions, you are making a big investment. Also make sure that your installer is actually a refrigeration technician that can repair your unit and properly commission it. There are many plumbers and electricians who install split systems as a side line that would have no idea how your units internals actually work let alone properly commission your unit for maximum performance and efficiency
– split systems
All split installers in all states are required to be licensed by the Australian Refrigeration Council and the person doing the wiring needs to hold a restricted electrical licence at a minimum. You should also get a certificate of compliance for the electrical work. This is very important as you will void your warranty if you use an unlicensed contractor. All systems have a 5year warranty so please take advantage of it by only using fully qualified personnel.

What is a multi-head split?

They are the best option for whole house cooling where you can’t run ductwork, i.e. a slab floor with a flat or cathedral roof.

What are the advantages of Ducted Systems?

Dedicated ducted splits offer the benefit of being an engineered package. You can zone the ducts to allow a smaller unit to cool sections of a house or office and turn off unwanted sections of a setup. A ducted system is preferable to multi head splits as they have fewer parts, fewer electronics and fewer potential refrigerant leaks. Having a humidity setting also allows the system to maintain a comfortable environment while only using around half of their potential energy thus making evaporative coolers redundant. Ducted systems also provide a much more accurate temperature control and uniformity.

What are the pros and cons of evaporative systems?

• Costs less to install in some instances.
• Costs less to run. (careful some units have 1600w fans which are not necessarily cheap to run)
• Allows you to vent heat from the house if it cools down outside by drawing in cool ambient air.

• Increases humidity.
• They can only cool relative to that day’s dew point.
• Generally require slightly more maintenance than air conditioning.
• Consider carefully before purchasing in water restricted areas or where dependant on limited water as water consumption can be up to 80 litres per hour.
An evaporative cooler requires doors or windows open to allow airflow. As a guide, the entire volume of the room should be flushed through every two minutes (or around 30 air changes per hour).
During winter, older ducted units on the roof should have covers placed over them and ceiling vents closed to stop heat loss. Alternatively, consider purchasing a unit with a motorised damper. (many new units have a automatic spring or gravitational shutter)