Most heat pump jobs in Australia are replacements, because most homes already have hot water. So this is the common case, not an edge case.
What qualifies
A registered air source heat pump water heater under 425 litres, installed by an eligible installer, can create STCs when it replaces an existing hot water system such as an electric storage or gas storage unit. The old unit does not need to be an eligible product itself. It needs to be the system being replaced, and that has to be evidenced. See which heat pumps are eligible.
Why the install type matters
The claim records whether the job is a new installation, a replacement or an additional system. The three are evidenced differently and the wrong box can make a claim fail. Our installation type guide explains each.
A replacement claim is built on proof that something was there before. A new installation, such as in a new build or where no system existed, has a different evidence trail.
Evidence for a replacement
- A clear photo of the old unit before it is removed, including its location.
- A photo of the old unit’s plate where readable.
- The new unit installed, its compliance plate and serial number.
- The install location and any plumbing or electrical connection.
- The signed assignment form.
How many STCs
The count does not depend on the install type alone. It comes from the registered model’s entitlement for your zone and install date, with a factor of 0.5 for 2026 and 0.4 for 2027, falling to 0.1 in 2030. At roughly $38 to $40 per STC at the time of writing, a replacement that registers 25 STCs is worth about $950 to $1,000 before installer margin. That 25 is illustrative only. See how many STCs a heat pump gets.
Replacing an existing heat pump
If the system being removed is already an eligible heat pump or solar water heater, check the rules first, because the scheme’s purpose is to support the move to efficient hot water, and different treatment can apply. Ask the regulator, or ask your trader to pre-check the job.
State certificates
A replacement in Victoria or NSW can also earn state certificates, subject to those schemes’ own rules. See VEECs and STCs on the same job.
What this means for you
If you are replacing a system, the discount is available. Make sure the model is registered, the install year is right and the old unit is photographed. For the step-by-step claim, see how to claim STCs on a heat pump, the hot water STCs page and pricing.