How much roof space does ducted air conditioning need?
The indoor unit sits in the roof space, with ducts running out to each zoned room. It needs room for the unit itself, room for the ducts to run without being squashed or kinked, and enough space for a person to get in to install and service it. Slimline ducted units are shorter than standard ones, which helps in lower cavities. There is no single height that suits every home, so we measure on site rather than guess.
Ducts also need clearance from the roof sheeting, which gets very hot in a Queensland summer, and from insulation that should not be crushed. Squashed ducts restrict airflow. That makes the system noisier and less effective.
Do I need to modify my ceiling for ducted air conditioning?
Some ceiling work is normal. The system needs a return air grille, which is a large opening where air is drawn back to the unit. Our rule of thumb is a 900 x 500 return grille for 10 to 14 kW systems and a 900 x 550 for 16 kW and above. Each zone also gets a ceiling outlet, and the unit needs an access point for servicing.
Bigger changes are sometimes needed. A bulkhead is a boxed-in section that drops below the ceiling line, often over a hallway, wardrobe or laundry, to carry a duct or unit through a tight spot. It is a common fix. Roof trusses are different. They hold up your roof and should not be cut or altered without engineering advice. That is not a shortcut we would suggest.
What if the roof cavity is too small and can't be expanded?
Expanding the cavity is rarely the sensible path. Raising a roof or changing its framing is building work with its own approvals and costs, and it is far bigger than an air conditioning job. In most cases there is a simpler route. The unit may suit a bulkhead, or a part of the roof with more height, with ducts feeding the tighter areas. Zones can also be laid out differently.
Some homes suit a different system. Skillion and cathedral ceilings have little or no cavity, so a split system may be the better answer there. Cost depends on access, duct runs, the number of zones, system size and any bulkhead or ceiling work. That is why a site inspection gives a more reliable figure than a phone guess.
How does Delta Temp check if ducted will fit?
We start with a free site inspection before any ducted quote. We look at the roof space, access, insulation, glass, ceiling height and orientation. We size the system by adding up the heat load of every zoned room at about 150 W per square metre, then choosing a system at about 70% of that total, because the zones are never all running flat out at once. In practice a 12.5 kW system suits 5 zones, about 120 m2 of zoned rooms, and a 14 kW suits 6 zones, about 130 m2.
The quote is fixed after the inspection, so you know the figure before work starts. We install brands including Fujitsu and Hisense, with zone controllers including AirTouch 5. We are QBCC licensed, ARC authorised and insured, and we service the Sunshine Coast from Caboolture to Noosa. Installations carry a 10 year workmanship warranty that covers defects in our installation work. Full terms are at deltatemp.com.au/warranty/. To book an inspection, call 1800 335 828.
