Hot water heat pumps

  • Use electricity to utilise heat energy from the ambient air or waste heat, to heat hot water for industrial processes and commercial heating.
  • Can replace more emission intensive equipment like gas califonts/instantaneous gas, fossil fuelled boilers, and older electric hot water units.
  • Supply hot water for domestic, commercial, and industrial situations, as well as industrial process heating requirements.
  • Suitable for sites with hot water requirements such as farming, food and beverage processing, cleaning and sterilisation, and process drying.
  • Commercially used for water and space heating in gyms, restaurants, hotels and aged care facilities.

Image left: supplied by Decarbonised Energy Solutions

Types of hot water heat pumps

How do hot water heat pumps work?

Electric hot water heat pumps operate on the principle of heat transfer. They use a refrigerant (ideally carbon dioxide, but could be propane, ammonia, or a synthetic chemical) that absorbs heat from the surrounding air or a waste heat stream. The refrigerant is compressed to increase the temperature, and then transfers the heat to water which can be used for heating purposes and industrial processes.

This process can supply heat more efficiently than heating the fluid through conventional means (e.g., a fossil fuelled boiler) because it is upgrading existing heat to a more useful form, which takes less energy than generating it directly.

Heat pumps and the electricity grid

Industrial and commercial hot water is a big energy user. Heating water in industrial and commercial businesses consumes nearly ten percent of all non-transport energy in New Zealand.

Most hot water heat pumps use energy from the New Zealand electricity grid, which is currently around 80 – 85% renewable, rather than a fossil-fuel fired heating system with a high emissions factor. A heat pump can deliver three or four times as much heat energy as the electricity put into it– making hot water heat pumps highly efficient.

Find out more about New Zealand’s electricity grid

New Zealand is moving away from fossil fuel use, and businesses need to start making changes now to futureproof their operations for a low emissions economy.

Benefits of heat pumps

  • Low emission - With New Zealand’s highly renewable electricity supply, electric heat pump technology can offer a low emission heat source for process heat applications, effectively displacing fossil-based heating. They do not produce as ash or flue gases
  • Low cost – The operating costs are around 45% to 75% of using a natural gas or coal boiler to produce the same amount of heat, which can lower yours (or your tenants) operational expenditure. Hat life-cycle costs, including maintenance and capital cost, are also typically lower.
  • Instant heating (and cooling) – Temperature can be controlled at the flick of a switch and can be turned on and off as needed or set to a timer. Some heat pumps can be used to meet both heating and cooling demands.
  • Safer with lower maintenance – Unlike combustion boilers, no part of the heat pump is ever at a temperature significantly higher than the output temperature, making them safer to operate with lower component degradation rate.


  • Smaller size - Fuel storage is not required. This may greatly reduce the physical size of the heating system compared to a fossil fuelled alternative. Some models are also much quieter.
  • Future proof – In the near future, our electricity grid will require demand response capabilities in equipment – heat pumps can offer this.
  • High efficiency – A heat pump system is more energy efficient than a fossil fuel or resistance electrical system (where heat is radiated to a room).
  • Versatile – Heat pumps can provide suitable replacements or additions to existing heating systems, or can be installed as an entirely new system. They come in a variety of sizes and can be cascaded in series to provide additional capacity if necessary.

Top tips for running your heat pump efficiently

  1. 1

    Understand your needs

    Heat pumps work most efficiently when the change in temperature between ‘source’ and ‘sink’ is minimised, which means that the warmest possible heat source should be utilised, and the coolest temperature delivered. Understanding your heating needs, and making sure that they are met (but not exceeded) will help achieve this.

  2. 2

    Look at the whole system

    Considering heat pump installation as a complete system can improve efficiency. Careful attention should be paid to the thermal storage and distribution system, which can affect the temperature of water supplied to the heat pump.

  3. 3

    Explore heat recovery

    Waste heat from other processes (such as air conditioning, heat pumps or cogeneration systems) can be used to heat water via a heat pump. This can greatly reduce energy input to the heat pump and deliver higher output temperatures.

  4. 4

    Monitor performance

    Ongoing monitoring of how a heat pump is performing is important for identifying issues and evaluating progress towards decarbonisation.

  5. 5

    Regular maintenance

    Your heat pump needs to be maintained according to your site-specific needs and manufacturer instructions, to ensure it continues to run safely and efficiently.