For a plumber, an air-source heat pump water heater is one of the better jobs on the board: a decent ticket, a customer who wants it done properly, and a discount that comes from certificates rather than from your margin. The catch is that the discount is only real once the paperwork is right and the certificates are paid.
This guide is the practical complement to our explainer on heat pump hot water STCs. It covers how to price the job, what to do on site, what goes wrong and how Victoria adds a second certificate. Always confirm figures against the Clean Energy Regulator (CER) register on the installation date.
What earns certificates
An eligible air-source heat pump water heater, or a solar water heater, installed to heat water for a home or business, can create STCs. Eligibility rides on the model: only models on the CER’s register as eligible can create certificates, registered by model and tank configuration, not by brand. The count depends on three things:
- The model’s registered figure, based on test results.
- The climate zone of the installation postcode.
- The deeming period, which shortens each year to 2030.
Use the CER’s published figure for the exact model. As an illustration only, a typical residential heat pump might create 25 STCs, which at $38 is $950 off the invoice. Real counts differ by model and zone. See heat pump hot water STCs and how many STCs a heat pump gets.
New, replacement or additional
The type of installation changes what is claimed and what evidence you need. A replacement of a working electric storage unit is not the same as a new dwelling build or an additional unit. Record the type correctly, and photograph the old unit when you are replacing one. The installation type resource explains the categories.
Price the job with the discount shown
Quote with a clear line: model, zone, number of STCs and dollar value at the date of installation. Customers who see the line understand where the discount comes from, and you avoid arguments if the count shifts. The heat pump STC calculator answer helps you check it.
| Quote line | Example |
|---|---|
| Heat pump supply and install | $3,800 |
| STC discount (illustrative 25 x $38) | -$950 |
| Net price to customer | $2,850 |
The numbers are illustrative. The point is that the discount only works if the certificates are created and sold, and until then you carry it.
What to collect on site
| Item | Detail |
|---|---|
| Assignment form | Signed by the owner, transfers the right to the certificates |
| Model and serial | Clear photo of the nameplate, legible |
| Installation photos | Unit in position, connections, geotagged |
| Old unit | Photo and note of what was removed, for replacements |
| Address and postcode | Must match the zone used in the claim |
| Install date | Same on invoice, compliance certificate and claim |
| Licence details | Your plumbing licence and, where relevant, electrical details |
| Compliance certificate | As required by your state |
Use the hot water and heat pump STC checklist as a template for the job pack, and the STC photo requirements for the photo set.
Where the claims go wrong
- Ineligible or removed model. The product was on the register at quote and off it at install. Check on the day.
- Wrong zone. The postcode in the claim differs from the install address.
- Missing or wrong signature. The assignment form is unsigned, or signed by someone who does not own the property.
- Date mismatch. The claim date differs from the compliance certificate.
- No old unit evidence on a replacement.
See why STC claims are rejected and top claim rejection reasons.
Victoria: the second certificate
In Victoria the same installation can also create Victorian Energy Efficiency Certificates under the Victorian Energy Upgrades program, which is run by the Essential Services Commission. VEECs trade at roughly $85 to $95 in 2026, with a reported $85 to $90 in September, so they are worth more than STCs per certificate, and the count and eligibility differ. The accreditation, record-keeping and audit rules are separate. Treat it as a second process, but collect the evidence once. See VEECs and STCs on the same job, the heat pump rebate stack and VEEC trading.
Getting paid
Plumbing businesses often run lean books, and a $950 discount on a $3,800 job is a quarter of the ticket. If certificates take 20 business days to pay, that quarter is yours to fund. With 10 heat pump jobs a month, about $9,500 is outstanding at any time on a long term, against roughly $450 on a one-day term. Choose a trader on net cash and settlement time, and read the cash flow guide.
A site routine
- Look up the model on the register, the zone for the postcode and the install year.
- Calculate the STCs and put the number on the quote.
- Get the assignment form signed before the job starts.
- Photograph the old unit, new unit, nameplate and connections.
- Check the date and address are the same on every document.
- Upload the same day, then fix anything the desk queries.
Solar water heaters follow the same process
Solar water heaters sit in the same scheme as heat pumps. The model must be registered, the zone and installation year drive the count, and the paperwork is the same: assignment form, model and serial photos, geotagged installation images and compliance documents. The main difference is the physical evidence: collector and tank installation, plus roof or ground mounting. See solar hot water STCs for the specifics.
Replacing a gas or old electric unit
Plumbers often replace gas storage or an old electric element unit with a heat pump. The evidence for the old unit matters, because it shows what was displaced. Photograph the old unit before removal, note its type, and keep the removal and disposal record. If the home is moving from gas to electric, check whether any state program or network incentive also applies, and confirm the rules on the relevant official page before promising anything to the customer. A quote that includes a stacked incentive that turns out to be closed is a margin problem for you.
What to do next
- Make a one-page job pack from the checklist and keep it in the van.
- Check how your trader handles hot water claims. See the hot water STCs page and how it works.
- Compare rates on pricing, and start trading when ready.