Ducted Reverse Cycle Air Conditioning: What to Know Before You Buy

A ducted reverse cycle system heats and cools your whole home from a central unit in the roof space, and done well it runs efficiently for well over a decade. Before you buy, a handful of factors decide how well it performs and what it costs to run. Here is what shapes a good ducted system, grounded in Australian standards and government guidance.

Ducts lose energy. Every ducted system loses some energy through its ductwork, which makes it less efficient to run than a wall-mounted split. [1] Leaks at poorly sealed joins and ceiling registers add to that, and air leaks can account for 15 to 25% of winter heat loss in a building. [2]

Good ductwork is insulated and sealed. A quality install uses ducts insulated to at least R1.5 with every join sealed, and a higher rating in extreme climates. [3] In older homes, leaky existing ducts will drag down a brand-new system, so the roof space is worth inspecting before installation. [4]

Zoning saves running costs. Zoning uses motorised dampers to heat or cool only the rooms you are using, rather than conditioning the whole house at once. [3] Conditioning empty rooms wastes energy, and zone settings can make a central system considerably more efficient. [1]

Design zoning from the start. Retrofitting zoning into an existing system is possible, but it costs more than building it in from the beginning. It is worth mapping how your household uses the home across the day before anything goes into the ceiling.

Strata can refuse an install. In a strata or body corporate property, an outdoor unit on common property is a modification that needs formal approval before any work starts, and refusals do happen. Committees can knock one back over external appearance, noise, limited space, or unapproved penetrations through shared walls.

Get strata approval in writing first. Approval is not automatic, even if other units in your building already have air conditioning. Skipping it can mean a penalty and an order to remove the unit at your own cost, so secure written approval before you buy.

Inverter vs non-inverter. A non-inverter compressor runs at full power then switches off, restarting at full power each time, which is energy-intensive and hard on the compressor. [5] An inverter uses a variable speed drive to ramp the compressor up and down to match demand instead of stopping and starting, holding a steadier temperature. [5][6]

Why inverters cost less to run. Inverter systems typically use 30 to 50% less energy than non-inverter models, and across a whole-home ducted system running long hours, that adds up over a season. They also run quieter and tend to last longer, since continuous operation causes less wear than repeated stop-start cycling. [6]

Sizing is the critical step. Correct sizing comes from a heat load calculation based on AIRAH's DA09 manual, which is built for Australian conditions. [7] An undersized system runs constantly and never quite gets comfortable, while an oversized one short-cycles, leaving the home cool but humid and wearing the compressor out faster. [7]

How proper sizing is done. A heat load assessment weighs floor area, ceiling height, insulation, window type and orientation, sun exposure, local climate and occupancy, not floor area alone.

For a properly sized inverter ducted system with quality ductwork and smart zoning, AC Wise connects you with vetted, licensed installers who size and build to standard. Request a no-obligation quote from an AC Wise partner.