What is a heat pump hot water system, and why is every Melbourne electrician suddenly selling them
If your gas or electric hot water system dies this year, the replacement quote will almost certainly include a heat pump option, probably heavily discounted. Here is what the technology actually is, before the rebate maths tempts you.
The one-sentence version
A heat pump hot water system is a fridge running in reverse: it pulls heat out of the surrounding air and pumps it into a water tank, using a compressor instead of a heating element.
Why that matters: the COP number
An old-style electric resistance tank turns 1 unit of electricity into 1 unit of heat. A heat pump moves 3 to 4 units of heat per unit of electricity, because moving heat is cheaper than making it. That ratio is the COP (coefficient of performance), and it is the single most important number on a heat pump spec sheet. COP 4 means roughly a quarter of the running cost of the old electric tank.
Pair it with rooftop solar and run it on a daytime timer, and water heating, usually a quarter of a household's energy bill, runs largely on sunshine.
Why the sudden sales push in Victoria
Three discounts stack on a heat pump hot water installation:
- Victorian Energy Upgrades (VEU) certificates give an upfront discount through accredited providers.
- Solar Victoria's hot water rebate: up to $1,000 for eligible households, and from July 2026 up to $1,400 for systems meeting local content rules.
- Federal STCs apply to heat pumps too.
Stacked, they can cover most of the price of a budget unit, which is why you see "$99 heat pump" style offers. That generosity attracts both genuine electrification and the shonky end of the industry, which brings us to the caution.
The honest caution
The rebate-chasing end of the market installs the cheapest possible units: noisy compressors outside bedroom windows, short warranties, poor cold-morning performance, and companies structured to disappear. A quality unit from an established brand costs more out of pocket but runs quieter, lasts longer, and actually delivers the COP on the box.
A heat pump is still usually the right call for a Melbourne home replacing gas or electric storage hot water. Just buy it like a 10-year appliance, not like a free government gadget.
On Thursday we publish the seven factors that separate a good heat pump from a rebate trap. Figures last checked 31 August 2026.