Why reverse cycle makes sense in Canberra
A heat pump doesn't need warm air to work. The ACT Government's guide points out that air at 0 degrees still has over 90% of the heat energy of air at 40 degrees, so there's plenty to pull indoors on a frosty Canberra morning.
The ACT Government is blunt about the alternatives: reverse cycle can be the cheapest to run, wood-fired heaters pollute and aren't recommended, and unflued gas heaters should be replaced immediately because of carbon monoxide.
Then there's supply. ACT electricity comes from 100% renewable sources, the government says, and new gas network connections have been prevented in residential zones since 8 December 2023.
The Canberra numbers to size against
Winter nights
July's mean daily minimum is 0.3 degrees at the Canberra Airport Comparison station, and the coldest on record is minus 10.0 degrees, in 1971.
Frost on the outdoor unit
With 117 frosts in 2006 and an average of 41 foggy days a year, defrost pauses are part of a Canberra winter. Mitsubishi Electric says the outdoor unit can stop for about 10 minutes to clear frost.
Cold zone on the label
The NCC lists Canberra as climate zone 7, and the energy rating label map puts it in the cold zone. Read the red heating stars for that zone.
Summer still counts
January's mean maximum is 28.8 degrees, with about 30 days a year reaching 30 degrees or more. Check the cooling capacity too, for the handful of 35 degree days.
Split, multi-split or ducted for a Canberra home?
| Split | Multi-split | Ducted | |
|---|---|---|---|
| Where the ACT guide fits it | Houses under 180 sqm, or a few rooms | Several rooms off one outdoor unit | Houses over 180 sqm |
| Average efficiency (CoP, ACT guide) | 3.7 | 3.7 | 3.5 |
| Zoning (ACT guide) | Switch on only the units you need | Very good: unused areas turn off | Limited to good, depending on system |
| Watch out for | Each bedroom needs its own unit | All heads share one mode, heat or cool | Old gas ducts can't be reused |
What to ask for on a Canberra quote
- Does this model have an 'H2' rating? The ACT Government's guide says to look for it for Canberra's winters.
- What's its heating capacity at 2 degrees outside, as well as the headline kW?
- How many red heating stars does it get in the cold zone?
- Was it sized from a heat load for the coldest room I use?
- Are you on the Brighte list, if I'm using an ACT scheme?
Loans and rebates for reverse cycle in the ACT
The Sustainable Household Scheme offers low-interest loans through Brighte for electric heating and cooling. Separately, the Home Energy Support program has a rebate category for reverse cycle heating and cooling, for eligible concession card holders who own and live in their home.
Two rules catch people out: quotes must come from suppliers on the Brighte list, and you shouldn't accept one until the ACT Government has pre-approved your application. Our ACT scheme guide covers eligibility.
What's on you, and what's on the installer
You can
- Note which rooms you heat on winter evenings, and which you cool in summer.
- Set it between 18 and 21 degrees on heat, as the ACT Government suggests. It says each degree warmer adds about 5 to 10% to running costs.
- Expect short defrost pauses on frosty mornings.
- Keep the outdoor unit clear and easy to get to.
Leave to a licensed installer
- The heat load, sized for winter.
- Choosing a model with enough capacity at 2 degrees.
- All refrigerant and electrical work.
- Disconnecting an old gas heater, which is a gasfitter's job.
What we'd do
If it were our home
We'd treat it as buying a heater. H2 rating, heating capacity at 2 degrees and red stars in the cold zone first, then a look at the cooling. If we qualified for the ACT rebate, we'd wait for pre-approval before accepting anything. And we'd want a reverse cycle specialist who sizes for Canberra winters, because Rinnai warns an undersized system leads to insufficient heating, and that's the mistake you feel every frosty night.
