Cutting the running cost of ducted air conditioning

Condition only the rooms you are using

The simplest saving with ducted air conditioning is not running it in rooms nobody is in. A ducted system can be split into zones, so you can run the living areas during the day and the bedrooms at night. The smaller the area the system has to hold at temperature, the less power it uses.

Shut the doors to rooms you are not using, including toilets, bathrooms and the laundry. Keep windows and external doors closed while the system is running, so the air you have paid to heat or cool stays inside.

If your system has no zoning, or the zones do not match how your household lives, ask an accredited member near you what can be changed with the system you have.

Set the temperature and let the timer do the rest

In summer, set the system to 25°C or higher. In winter, set it to 18 to 20°C. The Department of Resources, Energy and Tourism's Good Energy Practice Guides put each degree beyond those settings at up to 10 per cent more on the heating or cooling part of your bill.

Use the timer or program on your controller rather than leaving the system on all day. Have it come on shortly before you get home and ease back once everyone is in bed. On a hot day, start it early, before the house heats up, so it is not running flat out to catch up.

With a ceiling fan running you can set the air conditioner a few degrees warmer in summer and feel just as comfortable. Turn the fan off when you leave the room, because a fan cools people, not the air.

Keep the air moving freely

A ducted system moves a lot of air, so keep furniture, rugs and curtains clear of the ceiling outlets and the return air grille. Clean the return air grille, and clean or replace its filter just before summer and again just before winter. Do it more often if the system runs most days, the house is dusty or you have pets. As a rough guide, a clean filter can save 5 to 15 per cent of the system's energy use.

Ducts matter too. A hole or a loose joint in the roof space means you are paying to heat or cool the roof. Have a licensed technician check the ducts for holes and loose connections and fix any they find.

Book a service once a year, before the season you use the system most. A service catches small problems before they become expensive ones.

Look after the outdoor unit

The outdoor unit gets rid of the heat pulled out of your house in summer by moving air through its coil, so it needs room to breathe. Keep the area around it clear. Trim shrubs and foliage back at least half a metre, clear away leaves and grass clippings, and never stack things against it.

Shade helps. An outdoor unit in a shaded spot does its job with less effort than one in full afternoon sun, as long as the shade does not block the airflow. If yours sits in a tight or sunny corner, ask your dealer at the next service whether anything can be done about it.

When an old system should be replaced

An old fixed-speed ducted system switches on and off at full power to hold a temperature. An inverter system varies the compressor speed instead, so it holds the temperature steadily and uses less power doing it. As a rough guide, inverter models are about 30 per cent more efficient than fixed-speed units, with the higher purchase price recovered within a few years through lower bills.

If your system is getting on in years, costs more to run each season or needs repairs more often, ask an accredited member to look at it. A member sizes the replacement with a proper calculation, not a rule of thumb, and their written quote sets out the calculated capacity, the equipment, the outlets and zones, the price, the inclusions and exclusions, the warranty and how often it should be serviced.

If an installation falls short

Every new domestic installation by an accredited member is covered by the ACDA Guarantee: a written workmanship guarantee on contracts up to $25,000 including GST. If the work does not meet the ACDA Standards, ACDA engages an independent Chartered Engineer to investigate, report and arrange for the defects to be corrected. It is not an equipment warranty and not a price guarantee, and it applies alongside your rights under Australian Consumer Law.

If you have a concern about a member's work, complete the Dispute Resolution Form, attach your quote, your invoice and any photographs, and send it to the Dispute Resolution Committee at Air Conditioning Dealers Association Inc, PO Box 253, Emu Plains NSW 2750, or [email protected]. Equipment faults go to the manufacturer under its warranty, and your member can help you lodge that claim.

If your concern is running cost rather than the installation itself, start with the steps above and your dealer's service department.

Before each summer and winter

• Zones set to the rooms in use, doors to the rest closed
• Controller at 25°C or higher in summer, 18 to 20°C in winter
• Timer set around when the household is home
• Return air grille cleaned and filter cleaned or replaced
• Ceiling outlets and return clear of furniture, rugs and curtains
• Outdoor unit clear of leaves, foliage trimmed back half a metre
• Ducts checked for holes and loose joints at the annual service
• Annual service booked before the season starts

Every accredited member runs a service department that can check your ducts, service the system and advise on zoning or replacement, and a new domestic installation by a member carries the written workmanship guarantee on contracts up to $25,000 including GST.