How do heat-pump water heaters work?
A heat-pump water heater uses heat from the surrounding air to heat water in a storage tank. They work on the same principle as reverse-cycle air conditioners, by extracting heat from the air using a refrigerant gas that is then pressurised in a compressor. The pressurised refrigerant transfers the heat to the water in the storage tank (like a heat exchanger).
Heat-pumps and energy efficiency
A heat-pump water heater uses much less electricity than an electric storage water heater. This is because it only requires electricity to drive the compressor and the fan, instead of using electricity to heat the water directly, with an electric element.
What conditions are heat-pumps suited to?
The amount of heat transferred to the water in the storage tank depends on the surrounding air temperature. Heat-pump water heaters are therefore generally better suited to warmer climates and are not well suited to cool climates – especially where frosts occur regularly.
In cooler climates, the compressor will run for longer periods, which can result in greater energy consumption and a shorter life expectancy for the pump. A heat-pump water heater might be worth considering if a solar hot water system is not suitable for your household (due to lack of roof space or poor orientation for solar collectors), and electricity is your main fuel choice.
Heat-pump water heater incentives
There are two incentives available to Victorians replacing an existing hot water system with a heat-pump water heater:
- Small-scale Technology Certificates (STCs)
- Victorian Energy Efficiency Certificates (VEECs), also known as the Energy Saver Incentive.
Each incentive has varying eligibility requirements, so talk to your hot water supplier about what is available to you.