Heat Pump Water Heating: The Future of Hot Water

20 May 2024

Heat Pump Water Heating is providing New Zealand homeowners with a cost-efficient, sustainable alternative way to heat their water. By utilising heat from the surrounding air, heat pump water heaters need less energy to create hot water than traditional heaters that rely purely on gas or electricity.

Why is this important news for Kiwis?

Water heating is the third biggest energy use for NZ homes, utilising more energy on average than even personal vehicles. This means that by reducing your water heating energy consumption, you can also substantially reduce your overall household emissions, as well as your monthly energy bill. To put this in context, Rheem’s latest heat pump water heater – the Rheem Ambipower 280e – can save you over 70% of your water heating energy costs compared to traditional water heaters. Making the change to a heat pump water heater therefore provides both a tangible way for you to live more sustainably and substantially reduce your household energy costs.

How Heat Pump Water Heaters Work

How do heat pump water heaters use less energy to produce the same result? It’s all about how they make use of the natural heat in our air. Heat pump water heaters have a fan that draws outside air into the cylinder through inlet louvres. An evaporator is then able to absorb the heat from the air and transfer it into the water through a heat exchanger. The cold air is finally discharged through the air outlet louvres and released back into the atmosphere. This process continues until the required water temperature is reached – which means readily available hot water for the household. Even on cloudy or cold days, heat can be drawn from the surrounding air – but the efficiency of the water heater increases as the surrounding ambient air temperature increases. Rheem’s Ambipower heat pump range will operate when the ambient air temperature is between -6°C to 43°C, which means the electric element will operate when the ambient air temperature falls below -6°C or rises above 43°C. In short, heat pump water heaters will provide your home with hot water, no matter the conditions.

Unmatched Efficiency

The best way to work out the efficiency of a water heater is by looking at its Coefficient of Performance (COP). In short, the COP is the ratio of how much useful heat the water heater produces for water heating to the power input into the water heater. The higher the COP number, the more efficient the heat pump is. As heat pump water heaters extract heat from the surrounding air as opposed to purely generating heat through gas or electricity, they have a COP up to 4.5 times better than standard electric water heaters. This means that for every kw of power input, the heat pump will produce 4.5kw of useful energy!

Good for you and good for NZ

Household energy decisions account for 31% of emissions in our domestic economy¹, and with heating our hot water being high on the contributor list, us Kiwis have an opportunity to do some good for Aotearoa. In NZ, we aim to be leaders, and Rheem is working hard to produce sustainable products that contribute to our country’s efforts to reduce emissions. If you want to make the change to a heat pump water heater, head to Heat Pump Water Heating on the Rheem website to learn more, or speak to your local dealer.


[1] Rewiring Aotearoa, “Electric Homes: The energy, economic, and emissions opportunity of electrifying New Zealand’s economy.” Released March 2024.

AmbiPower Heat Pump Water Heater

Rheem Ambipower 280e

Rheem AmbiPower 280e