Ducted aircon Melbourne, cost, install, and what to spec in 2026

Ducted air conditioning is the highest-value upgrade for a Melbourne family home that's outgrown single-room splits. Done right, one system cools and heats the entire house from a single controller with per-zone setpoints. Done wrong, undersized, badly ducted, no zoning. It costs more to run than four separate splits and never quite gets cold enough on a 38°C day.

This is what we tell every Berwick, Officer, Cranbourne and Clyde-North family that rings us for a ducted quote.

Retrofit or new-build, the pricing gap is big

If your house was built with ducted rough-ins from day one (most Clyde North, Officer South, Selandra Rise new builds after 2018), install is straightforward, indoor and outdoor unit plus connection, usually $6,500-$9,000. If we're pulling ducts through an existing weatherboard or 90s brick veneer where nothing was pre-run, add $2,000-$4,000 in duct + ceiling access labour.

We check the ceiling void on the quote visit. Standard 300mm void with truss access = straightforward. 200mm void or hip-roof with no truss access = harder, and we spec the slim-line SEZ-KD indoor rather than a normal PEAD-M. Not a deal-breaker but affects the price.

Sizing, the load calc that matters

For a typical Melbourne double-storey brick veneer of ~200m² living area with average glass:

• Small 3-bed single-storey (~120m²): 10-12.5 kW
• Standard 4-bed single-storey (~160-180m²): 14 kW
• 4-bed double-storey (~200m²): 16 kW
• Larger great-room double-storey with high glass (>250m²): 18-22 kW

We do a proper heat-load calc on any job over 14 kW, measures the glass area, insulation R-value, and orientation. Skip this and either you get an oversized system that cycles constantly (expensive to run, hard on the compressor) or an undersized one that can't hold setpoint on 35°C+ days.

Zoning, the single biggest efficiency win

Never install a ducted system without zoning. Non-negotiable. A 4-zone Zonemate controller lets you shut off unused rooms, kids' bedrooms during the day, living zones at night, and cuts running cost by 30-40% over an always-on ducted setup.

Our default recommendations by house size:

• 3-bed single-storey: Zonemate 4-zone (living, master, kids, study/bathroom)
• 4-5 bed single-storey: Zonemate 6-zone
• Double-storey: Zonemate 8-zone (per bedroom + living zones, upstairs/downstairs split)

Variable-speed dampers (VSD) are worth the extra ~$60 per zone if you want proportional airflow rather than just on/off. Nicer comfort in less-used zones, 30% airflow to the study, 100% to living, all controlled from your phone.

Brand pick for the ducted head unit

Mitsubishi Electric PEAD-M is our default mid-static indoor unit. Long duct runs or 6-plus zones want the PEA-RP high-static instead, because static pressure rather than capacity is what starves the far bedroom. Shallow ceiling voids get the SEZ-KD slim-line. Kaden Ducted is the other route, on the same ductwork and the same zoning, and it's what makes a whole-house job happen in one visit rather than in stages.

What a Melbourne ducted install actually costs

Fully installed, includes indoor + outdoor unit, all ducting to 4-6 zones, Zonemate controller and dampers, compliance certificate, warranty registration:

• 10 kW Kaden Ducted, 4-zone: $6,890
• 12.5 kW Kaden Ducted, 6-zone: $7,990
• 14 kW Kaden Ducted, 6-zone: $8,590
• 14 kW Mitsubishi PEAD-M, 6-zone: $10,490
• 18 kW Mitsubishi PEA-RP, 8-zone: $14,490

Retrofit adds $2,000-$4,000 to any of these numbers. Ceiling access work, patch and paint, and roof-cavity duct pulling isn't quick.

What separates a $9k quote from a $12k quote

Same-brand indoor unit, similar kW rating, but a $3,000 gap. That gap is almost always:

• Zone count (4 vs 8) and damper type (constant-speed vs variable-speed)
• Duct diameter and insulation grade (R1.0 flexi vs R1.5 rigid)
• Return-air grille size (undersized returns choke airflow)
• Length of copper line run and refrigerant top-up
• Extras: Wi-Fi module, roof-access hatches, external condenser stand

Ask any competing quote to itemise these. A quote that's dearer because the ducts are R1.5 and the returns are sized properly is a different thing from a quote that's dearer for no stated reason, and you can only tell the two apart once it's itemised.