Heat pump hot water installation: what to expect

Why the regulators are watching

In March 2024, Solar Victoria, the Essential Services Commission, the Victorian Building Authority (now the Building and Plumbing Commission), Energy Safe Victoria and WorkSafe Victoria joined forces to improve the compliance of heat pump hot water installations, after rapid growth under the Solar Homes and Victorian Energy Upgrades programs. In NSW, Building Commission NSW inspectors carry out inspections of heat pump installations and published advisory notes in 2025 for both plumbing and electrical work. None of this means heat pumps are risky — it means a rebate-driven rush let some corner-cutting through, and you are entitled to the job done to standard.

The licences involved

A heat pump install can touch up to three trades, and each part needs the right licence:

• Plumbing (always). Connecting the water side is plumbing work. In Victoria, the BPC says a self-contained unit needs a plumber accredited in water supply.
• Refrigeration (split systems). If the install involves connecting refrigerant pipework — as split systems with a separate outdoor compressor do — Victoria also requires a refrigerated air-conditioning accreditation (there is a class restricted to split system heat pump water heaters).
• Electrical (always). Energy Safe Victoria says the wiring, circuit protection and isolator for a hot water service must be installed by an A-class licensed electrician working under a registered electrical contractor.
• Gasfitting (if you're leaving gas). Removing a gas water heater is gasfitting work, and the old gas pipe has to be sealed properly — the BPC calls non-compliant capping “dangerous” and says it has received numerous complaints about it. Our heat pump vs gas guide covers the switch itself.

Every installer listed on HotWaterLocal links to their own website, so you can check who they are before you call. When you get a quote, it is reasonable to ask who will do each part and what licences they hold.

Where the unit goes

The BPC says heat pump water heaters must be installed in well-ventilated areas, typically outdoors, and that installing them below covered clearances is a compliance issue its audits have found. It also recommends placing them away from bedrooms and where they won't disturb neighbours, away from flammables like paints and mineral oils, and avoiding high-salt and corrosive spots. NSW's electrical note makes the same point from the other side: outdoor units installed indoors overheat and lose efficiency. Our noise guide covers the night-time rules that make placement matter.

Underneath it, NSW's plumbing note says the tank must sit on a level, stable and impervious base — a cast concrete slab at least 75mm thick, or a 50mm pre-cast one — and inspectors have found tanks installed directly on dirt.

What inspectors keep finding wrong

Building Commission NSW's two advisory notes (issued February 2025, updated 14 March 2025) list the recurring problems. You don't need to understand the standards to look for most of them:

• Relief valve drain. The temperature/pressure relief valve line must end where a release of steam or hot water won't cause a nuisance, at set heights above a gully, gravel pit or open ground — not just cut off mid-air.
• No pressure limiting valve. Installers must test the incoming water pressure and fit a pressure limiting valve when it is needed. Inspectors found installs without one.
• Pipe insulation. Inlet, outlet and relief pipework needs insulation to a minimum R-value; inspectors found it missing or fitted wrongly.
• The base. Tanks on bare dirt or poorly supported, as above.
• Electrical. A Type A RCD protecting the circuit, a local isolator that can be locked off, and weatherproof conduit that keeps water out.

Energy Safe Victoria adds that the isolating switch goes next to, but not on, the unit, that all final sub-circuits in a home need RCD protection, and that if the manufacturer specifies a dedicated circuit, that is what must be installed.

The paperwork you should get

In Victoria, the BPC says a compliance certificate must be issued by a licensed plumber for heat pump water heater installations above the monetary threshold, by the plumber who did or supervised the work — and if one plumber disconnects the gas and another installs the heat pump, each issues their own. On the electrical side, Energy Safe Victoria says a certificate of electrical safety must be completed whenever a hot water service is installed, new or replacement. Other states have their own versions of both.

Ask for copies before you settle the final invoice, and keep them with the warranty card and the model details. They are your proof the job was done to standard, and rebate programs can ask for evidence of installation. Our state-by-state rebate guide has the conditions for each program.

A simple checklist for install day

• Before: the quote says who does the plumbing, electrical and (if relevant) gas work, and what is included — position change, pipe re-run, circuit work, removal of the old unit.
• Position: outdoors with open air around it, clear of bedroom windows and the neighbour's fence where possible, not boxed in under a low cover.
• Base: a solid, level slab, not dirt or pavers on sand.
• Relief drain: piped to a proper discharge point, not ending in mid-air beside the tank.
• Electrical: an isolator switch beside the unit (not on it), and wiring in sealed conduit.
• Settings: ask how the timer is set — copying an old overnight off-peak schedule isn't always cheapest for a heat pump (see our electric-to-heat-pump guide).
• After: plumbing compliance certificate, electrical safety certificate, warranty registration and the model number written down.

Frequently asked