What decides the cost of a ducted system?
The price follows the job, not the label on the house. The main drivers are the capacity of the system, the number of zones, the length and complexity of the duct runs, how hard the roof space is to work in, any electrical work needed, and the brand and zone controller you choose. Each one adds equipment or labour.
Two houses with the same number of bedrooms can need very different systems. A single storey home with a roomy roof space is simpler than a tight roof or a second storey. That is why a number over the phone is a guess, and we would rather not guess.
How big a ducted system does a 3-bedroom house need?
We size ducted systems by adding up the heat load of every zoned room at about 150 W per square metre. Then we size the system at about 70% of that total, because the zones are never all running flat out at once. As an example, 100 m2 of zoned rooms is about 15 kW of load, which points to a system near 10.5 kW.
In practice a 12.5 kW system suits 5 zones (4 bedrooms plus an open kitchen, living and dining), about 120 m2 of zoned rooms. A 14 kW suits 6 zones, the same plus a media room or similar, about 130 m2. A 3-bedroom house often has fewer zones than those examples, so the system may be smaller. The inspection adjusts for insulation, glass, ceiling height and orientation, so the final size is worked out on site.
Is ducted worth it for just two bedrooms?
Ducted is built to serve several rooms from one unit. With only two bedrooms, the fixed parts of the job are spread over fewer rooms. These are the indoor unit, the roof work, the controller and the installation. That can make ducted poor value per room.
A split system in each room can suit a small number of rooms better. Ducted can still make sense if you also want the living area cooled from the same system, or you want hidden equipment and just grilles in the ceiling. We will tell you which way to go after we have seen the house.
What changes if I am replacing an existing system with ducted?
A replacement has extra steps. The old system has to be removed and the refrigerant recovered, which needs an ARC authorised installer. If you already have ducting, its condition and size matter. If you are moving from split systems to ducted, new ducting goes into the roof space.
Return air is one detail that often gets missed. As a rule of thumb, we fit a 900 x 500 return grille on 10 to 14 kW ducted systems, and a 900 x 550 on 16 kW and above. A return that is too small makes the system work harder and move less air. An old return grille is not always big enough for a new unit.
How does Delta Temp quote a ducted system?
We start with a free site inspection. We check the roof space, the rooms to be zoned and the electrical side, then give you a quote. The quote is fixed after the inspection. We install brands including Fujitsu and Hisense, with zone controllers including AirTouch 5.
Our installations carry a 10 year workmanship warranty. It covers defects in our installation work only. It does not cover equipment faults, which fall under the manufacturer warranty (Fujitsu 5 years, Hisense 7 years, parts and labour), fair wear and tear, or lack of servicing. Full terms are at deltatemp.com.au/warranty/. Finance is available through humm, always subject to approval by humm.
