Is it a ducted system or a split system?
The answer starts here. A split system has one indoor unit that cools the room it is in, and a bit of the space around it. It will not cool a bedroom down the hall. If you expected it to, the system is working as designed and the fix is another unit or a different layout.
A ducted system has one indoor unit in the roof and ducts running to vents in each room. It should cool every zoned room. If it does not, something is wrong with the airflow, the settings or the size of the system.
Why does ducted air conditioning cool some rooms and not others?
Most uneven ducted cooling comes down to airflow. The cold air has to get through the ducts, out the vents and back to the unit through the return grille. If any part of that is restricted, the rooms at the end of the run suffer first.
Common causes are a zone closed on the controller, a zone damper stuck or set too low, and flexible duct that has been crushed, kinked or pulled off its collar in the roof. Leaking joints also dump cold air into the roof space instead of the room. On the Sunshine Coast the roof gets very hot in summer, so poorly insulated ducts lose a lot of cooling before the air reaches the room.
Could the system be the wrong size for the house?
Yes. A system that is too small struggles on hot afternoons, and the rooms with the most sun or glass fall behind first. Extra rooms added after install, or zones that have been opened up, can also push a system past what it was designed for.
Here is how we size ducted systems. We add 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. 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.
What can I check before I call someone?
A few things are safe to check yourself. Make sure every zone you want is switched on at the controller, such as AirTouch 5 if you have it. Check the return air filter and clean it if it is dirty. Make sure no furniture, rugs or curtains are blocking vents or the return grille, and keep internal doors open or undercut if the room has no other way for air to return.
Close blinds on sun facing windows, and keep the outdoor unit clear of leaves, boxes and garden growth. If none of that helps, stop there. Duct work in the roof is hot, dark and easy to fall through, so leave it to a licensed technician.
How does Delta Temp handle uneven cooling?
Delta Temp Climate Solutions is based in Baringa and services the Sunshine Coast from Caboolture to Noosa, not Gympie. We have installed more than 1,000 systems across the region, and we work with Fujitsu and Hisense, which we install as an authorised dealer.
For a new ducted system we do a free site inspection first. We look at the roof space, the zones, the return air and the heat load of the home, then give you a fixed quote after the inspection. Most Sunshine Coast homes land between $11,000 and $18,000 installed, and larger homes can reach about $22,000, depending on home size, zones and roof space.
Keep reading
- What size ducted air conditioning system is right for my home, and is 12.5kW or 14kW enough?
- Can ducted air conditioning be installed if my roof cavity is small or needs ceiling modifications?
- What size or capacity air conditioner do I need for my home or multiple rooms?
- Can ducted air conditioning control temperature per room or run just one zone, such as a bedroom at night?
