Water heating is one of the largest energy users in the average Australian home, and it is the one almost nobody thinks about until the tank dies on a Sunday.
That is a shame, because it is also one of the few household decisions where the technology has genuinely improved. A heat pump hot water system does the same job as the tank it replaces while using a fraction of the energy, and there is a federal scheme that takes a chunk off the installed price.
Here is how it works and who it actually suits.
The fridge comparison, and why it is accurate
Your fridge does not make cold. It removes heat from inside the cabinet and dumps it out the back, which is why the coils behind your fridge are warm.
A heat pump hot water system runs that same process pointed the other way. It pulls warmth out of the surrounding air and moves it into your water tank. The air it exhausts is cooler than the air it drew in, because the heat has gone into your shower.
This is the whole trick, and it is why the efficiency numbers look strange next to a conventional system. You are not paying to create heat. You are paying to run a compressor and a fan that relocate heat that was already sitting in your laundry or on the side of your house doing nothing.
How it compares to what you have probably got
Electric storage. A resistive element sits in the tank and glows, converting electricity to heat at a strict one to one ratio. Simple, cheap to buy, and the most expensive common option to run. A heat pump does the same job for a fraction of the input energy.
Gas storage or instantaneous. Burns fuel to heat water either in a tank or as it flows. Generally cheaper to run than electric resistive, but you are buying fuel continuously and gas pricing has moved in the wrong direction. It also requires a gas connection, which not every property has or wants.
Solar hot water. Genuinely efficient when the sun cooperates, but almost every solar system needs a booster for cloudy stretches and winter. A heat pump does not depend on sunlight at all, so its output is far more predictable.
The bit that makes the maths work: STCs
Every eligible heat pump hot water installation in Australia attracts Small scale Technology Certificates under the federal scheme.
Here is the part people find surprising: you do not apply for anything. There is no form, no waiting, no cheque in the post. Your accredited installer creates the certificates at the point of installation, assigns them to a registered agent, and the value comes straight off your quoted price as a point of sale discount.
The amount varies based on your postcode and climate zone, the specific model and its rated capacity, and the certificate spot price at the time.
Two things worth knowing:
The deeming period steps down annually. The scheme is legislated to wind down over time, and the number of certificates a system earns reduces each year. Waiting does not improve your position.
Some states add their own scheme on top. Victoria in particular runs an active state level program alongside the federal one. Eligibility rules and values differ by state and change periodically, so confirm current details for your address before you commit.
Ask your installer for the current value at the time of quoting rather than relying on a figure you read in an article, including this one.
Where to put it, and why placement matters
This is the practical detail most articles skip, and it is the one that determines whether you are happy with the system.
A heat pump needs airflow. It is pulling heat out of the air, so it needs a steady supply of air to pull from. Boxing a unit into a tight, sealed alcove starves it, and a starved heat pump works harder for less.
It also makes noise. There is a fan and a compressor, so it is not silent. Positioning one directly outside a bedroom window, or hard against a neighbour's boundary next to their bedroom window, is a decision you will revisit.
The exhaust air is cooler than ambient, which is mildly useful in some spots and mildly annoying in others.
Get placement discussed properly at quoting stage rather than discovering it on installation day.
Who it genuinely suits
Good fit: households replacing electric storage, anyone on a property without gas, homeowners planning to stay put long enough to bank the running cost savings, and anyone with solar PV who can run the system during the day on their own generation.
Think harder: apartments with no viable outdoor placement, properties where noise and airflow constraints cannot be resolved, and anyone who needs a same day replacement for a failed tank and cannot wait for a proper install.
Frequently asked questions
Does it work in cold weather?
Yes, though efficiency drops as ambient air cools. Most systems include a backup element for the coldest conditions or unusually high demand. Cold climate installations need this factored into the specification rather than assumed.
How long does it take to recover after a big hot water demand?
Longer than a gas instantaneous system, which never runs out, and comparable to or better than electric storage. Correct tank sizing for your household is what prevents this becoming an issue.
Can I run it on my solar?
Yes, and it is an excellent pairing. Timing the heating cycle for the middle of the day means running it largely on your own generation.
What maintenance does it need?
Keep the air intake and surrounds clear, and follow the manufacturer's servicing schedule. The tank itself has the same anode and valve requirements as any storage system.
Next steps
If your existing tank is on borrowed time, it is worth making the decision before it fails rather than in a panic on a weekend.
Have a look at the EvoHeat hot water heat pump range. For larger installations, there is a separate commercial hot water system range.
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