What affects the cost of heat pump hot water installation?

A heat pump water heater moves heat from the air into the water using a fan, compressor and refrigerant circuit. Integrated units have everything in one package on a single base. Split units keep the tank in one place with a separate outdoor heat pump joined by pipework, which can suit tight spots but adds work.

Tank size should follow how many people live in the home and when they use hot water, not the size of the old tank. A heat pump stores water rather than heating it on demand, so it has to cover your busiest stretch, such as back-to-back showers before work. Too small and you run out; too big and you pay for capacity you never use.

The simplest place for a new unit is usually where the old one was, because the water pipes and cable are already close. But a heat pump needs things an old tank didn't: fresh air, room for its chilled exhaust, a level base, a drain for condensation and space for servicing. It hums while it runs, so a spot under a bedroom window may not suit.

Moving it adds plumbing by a licensed plumber, a new base and a longer cable run. A wall-hung gas continuous-flow unit leaves no base at all, so a heat pump replacing one needs a pad on the ground. On narrow blocks, getting a full-size tank down a side passage can also take planning.

Replacing gas hot water adds steps. A licensed gasfitter caps the gas to the old unit, and a gas storage unit's flue may need removing with the roof or wall made good. A licensed plumber connects the water. Your quote should name who does each part of the job.

From 1 March 2027, a gas hot water system in an existing home that breaks and can't be repaired must be replaced with an electric alternative, unless an exemption applies. You don't have to replace a working unit, but planning the change before it fails gives you time to choose the spot and sort the circuit.

A gas water heater has no circuit of its own, or only a small supply for its controls, so a heat pump replacing it usually needs a new dedicated circuit, safety switch protection and an isolator at the unit. Energy Safe Victoria's guidance on the Wiring Rules says every final sub-circuit in a home, the hot water circuit included, needs RCD protection.

A board with a spare position and modern protection makes that straightforward. A full board, or one with old fuses, may need work first, which should appear as its own line. Replacing an electric tank is different: the existing circuit may be reused, but how it's switched matters.

Many electric tanks run on an off-peak circuit that only switches on overnight. That suits an element, but night is the coldest part of the day for a heat pump. With solar, a timer set to the middle of the day lets it heat on your own power. Without solar, it's set around your tariff.

Changing how the circuit is switched, adding a timer or moving the unit off a controlled load all change the electrical scope, so tell the installer about your solar and tariff when you ask for a price.

The old unit has to be drained, disconnected and taken away. An old heat pump holds refrigerant, and releasing regulated refrigerants into the air is illegal, so it's recovered by a licensed technician before the unit leaves. Flue removal and patching where a wall-hung unit was mounted also belong in the quote.

Get the full price in writing before work starts, with each trade's part listed. Hot water services are non-prescribed electrical work, and the electrical side ends with a Certificate of Electrical Safety.