Upsizing Air Conditioning in Canberra — When the Unit Is Too Small for the House
If one Canberra room is fine and the rest of the house never reaches set point, the system is often undersized, not due for a service. Green Air Heating and Cooling in Fyshwick measures the house, the existing unit and the ductwork, then quotes an upsize, extra heads, or a different fix. An AirTouch controller will not add kilowatts. Call 0412 794 558 for a sizing assessment.
Book a sizing assessmentCall 0412 794 558
How do I know the air conditioner is too small?
Common signs in ACT homes:
- Living areas never hit the set temperature on a hot afternoon or a −5 °C morning
- The outdoor unit runs almost continuously
- One wing or the upstairs is 3–5 °C adrift from the thermostat
- You added a room, a rumpus, or converted a garage after the original install
- An evaporative cooler that used to be enough now feels like a fan
A dirty filter can mimic this. So can collapsed ducts, closed dampers, or a dead zone motor. That is why the first visit is a diagnosis, not a new outdoor unit on the trailer.
Upsize, extra split, or AirTouch?
| What you notice | Likely cause | Right page |
|---|---|---|
| Whole house never gets there, unit at full tilt | Capacity too low | This page — upsize or replace |
| Some rooms starve while others freeze | Zoning / airflow, plant still sized OK | AirTouch 5 upgrade |
| One new room or granny flat is the only problem | Extra split or multi-head | Granny flat / garage or a split add-on |
| System is dead or leaking | Repair or replacement | Repairs or installation |
Green Air will not sell an AirTouch 5 as the fix for an undersized plant.
Which Canberra houses hit this first?
Undersizing shows up most in older, leakier fabric and in gas-to-electric changeovers:
- Woden and Weston Creek 1960s–70s brick veneer
- Tuggeranong 1970s–80s family homes with later rumpus rooms
- Belconnen suburbs such as Kaleen, Evatt, Melba, Florey and Hawker
- Gungahlin houses that still run gas heating and a cooling system that was never sized as the only plant
- Inner North and Inner South extensions that kept the original small split
New Molonglo all-electric homes are less often an upsize job unless the original design was light.
Evaporative to reverse-cycle, or gas ducted to reverse-cycle
Canberra evaporative cooling does little on humid or still days and does not heat. Replacing it with reverse-cycle is an upsize-class job: new indoor, outdoor, often new ducts.
Replacing ducted gas heating with reverse-cycle is the other common path, especially after the ACT stop on new gas network connections. If you are an ActewAGL electricity customer in the ACT, ask at quote whether an ActewAGL heating and cooling upgrade can apply. NSW addresses cannot use it.
Eligible ACT households can also ask about Sustainable Household Scheme finance. New loans have been 3% since 1 July 2025.
What the sizing visit covers
- Measure rooms, ceiling height, glazing and insulation, not just floor area.
- Identify the existing plant (kW, age, refrigerant, duct condition, zone motors).
- Separate capacity problems from airflow and control problems.
- Quote the smallest change that actually holds set point: larger ducted unit, extra indoor heads, duct repairs, or a full replacement.
- Put make, model and capacity in writing.
What we will not do
- Quote a bigger unit off a phone photo
- Promise a dollar-from price
- Treat AirTouch as extra heating capacity
- Install new ducted gas heating
Book a sizing assessmentCall 0412 794 558
Frequently asked questions
Why is my air con not cooling the whole house in Canberra?
The plant may be undersized, the ducts may be leaking or crushed, or the zoning may be sending air to the wrong rooms. Green Air checks capacity and airflow before quoting a replacement.
Can I just add another split upstairs?
Sometimes. If the rest of the ducted system is healthy, an extra split for a hot upper floor is cheaper than ripping out the plant. If the ducted unit is already at its limit, a split only masks the problem.
Will a new thermostat fix it?
Only if the fault is control or zoning. A thermostat cannot create kilowatts. If the outdoor unit is already at maximum, you need more capacity.
Do you upsize evaporative cooling?
We replace evaporative cooling with reverse-cycle where that is the right thermal solution. We do not boost an evaporative unit to do reverse-cycle work.
Is Gungahlin too new for this?
No. Plenty of Gungahlin homes still run gas heating and a cooling system that was never designed as the only year-round plant. We assess rather than assume.