Sanden Eco CO2 Hot Water heat pump COP 5 most efficient Japanese Australia

The Sanden Eco PLUS Heat Pump hot water system is Australia's leading renewable hot water service. 

Pure Electric is your home for the Sanden Eco PLUS, why consider the PLUS?

  • Highest efficiency heat pump in Australia (COP 5 – uses 0.9kW of energy to generate 4.5kW of heat) - your home leader!
  • Quietest hot water heat pump system in Australia, just 37dB - no home is complete without happy neighbours!
  • 15 year Tank Warranty (Australian made, stainless steel) and 6 year Heat Pump warranty - no worries!
  • Utilise with your rooftop solar PV system using the “blockout timer” for near zero grid imports - smash emissions, smash bills

Make your all electric home with Pure Electric today, your home for the Sanden Eco PLUS.

Frequently Asked Questions about the Sanden Eco® PLUS Hot Water Heat Pump

If you have a question about the Sanden Eco® PLUS Hot Water Heat Pump System that is not listed here, please email us and we'll find the answer for you.

1. Is the Sanden Eco® PLUS Hot Water Heat Pump System an energy efficient hot water system? How does it compare to a conventional electric hot water system?

You can save up to 80% of your conventional electric hot water energy costs!  The Sanden Eco® Plus Hot Water Heat Pump uses only 20% of the energy required by an electric storage hot water system. <1/13th compared to gas hot water systems which have a COP <0.9!

2. What are the benefits of the Sanden Eco® PLUS Hot Water Heat Pump System?

Not only does a Sanden Eco® Plus Hot Water Heat Pump help save on energy costs, it also delivers:

(a) The Heat Pump Unit

  • Innovative technology -- up to 50% faster heat recovery than currently available Hot Water Heat Pumps.
  • Industry leading quality & performance, with the highest level of STC values of currently available Hot Water Heat Pumps.
  • Class leading warranties, backed by Sanden’s 35 years of operation in Australia.

(b) The Stainless Steel Storage Tank

  • High quality, extra long life duplex stainless steel cylinder.
  • Two x 315 litre Tank sizes to suit your space requirements (tall with a reduced diameter or short with an increased diameter) - tall or short
  • Fully insulated for extremely low heat loss
  • Safety pressure and temperature relief valve
  • Mains pressure rated

3. How does a heat pump hot water system work?

The Sanden Eco® Plus Hot Water Heat Pump operates like a refrigerator in reverse. It contains a fan that forces air through an evaporator that contains a refrigerant. The heat in the air passes through the evaporator and is absorbed by a natural refrigerant, R744 (CO2), which is ozone friendly and does not contribute to global warming.

The warm gaseous refrigerant is circulated in the system via a compressor. As it passes through the compressor, its pressure rises, as does its temperature. This hot refrigerant then passes through a heat exchanger to heat the water, which is finally pumped to the storage tank.

Sanden HP

4.  Which hot water system should I choose?

Sanden has 4 hot water systems to choose from, model numbers GAUS-315EQS (short, fat tank) and GAUS-315EQT (tall, thin tank) have a tank size of 315L, model number GAUS-250EQTB has a tank size of 250L and model GAUS-160EQTB has a tank size of 160L. Which one you choose depends on the space requirements of the location where you are installing it and we can definitely assist you here! Give us a call - 1300 TO PURE (1300 86 7873)


5. I don’t understand the use of a CO2 refrigerant by the Sanden Eco® Plus Hot Water Heat Pump System.  Isn’t CO2 a greenhouse gas and therefore harmful to the environment?

Yes, but CO2 has a Global Warming Potential (GWP – see below for explanation) of 1. Carbon dioxide is the baseline measurement of how it will contribute to global warming for a given mass.

Our system utilizes less than 1 kg of R744 (CO2) as a refrigerant contained in a closed system at the factory.  The installer does not need to charge the heat pump on site.

Global warming potential (GWP) is a measure of how much a given mass of greenhouse gas is estimated to contribute to global warming.. It is a relative scale which compares the gas in question to that of the same mass of carbon dioxide (whose GWP is by convention equal to 1). A GWP is calculated over a specific time interval and this time interval must be stated whenever a GWP is quoted or else the value is meaningless.


See also:

6. Why does Sanden Eco® Plus Hot Water Heat Pump System use CO2 as a refrigerant?

  • There is far less environmental impact (i.e. No ozone layer depletion and minimal global warming) than other commonly used refrigerants, should the system leak. 
  • There is a much higher efficiency, thereby allowing more heat to be transferred to the water, for less energy used (i.e. Excellent  thermodynamic ability).

7. What is the noise level of the Sanden Eco® Plus Hot Water Heat Pump System?

The unit is rated at 37dB (measured at 1 metre distance from the unit), which is almost silent. By comparison, a whisper is around 30dB and inside a library is approximately 40dB.

8. How do I purchase a Sanden Eco® Plus Hot Water Heat Pump System?

Call Pure Electric now on 1300 TO PURE (1300 86 7873).

9. What is the life expectancy of the Sanden Eco® Plus Hot Water Heat Pump System?

The Sanden HWHP is designed to last for 15 years. The high quality, weather resistant construction of the Eco® Plus Hot Water Heat Pump System outdoor module carries a warranty of 6 years, whereas the high quality, extra long life stainless steel storage tank carries a class leading 15 year warranty.

10. At what temperatures will the Sanden Eco® Plus Hot Water Heat Pump System operate effectively?

The Sanden HWHP will operate effectively between minus 10 and plus 43 degrees C, without the need for an electric booster element. It is also fitted with in built freeze protection, making it suitable for all climates.

11. Does the Sanden Eco® HWHP require the assistance of an electric booster element to heat water, when outside ambient temperatures are very low?

No, unlike other competitor HWHP systems, the Sanden Eco® HWHP system does not require an electric booster element

12. Can I operate the Sanden Eco® Plus Hot Water Heat Pump System on Off-Peak Tariffs?

Yes, please refer to the Installation Manual for details. There are no special settings for off peak connection. Simply ensure that the off peak tariff supplies a minimum of 5 hours continuous power to the Sanden HWHP.

13. What are RECs and STCs and what are they worth?

The purchase and installation of a Sanden Eco® Plus Hot Water Heat Pump entitles you to Small-scale Technology Certificates (STCs) – formerly known as Renewable Energy Certificates (RECs). For more information: visit and

The Sanden HWHP achieves the highest level of STCs of any hot water heat pump, currently available in Australia, and these are as below:


14. Is water quality an important consideration for the Sanden Eco® Plus Hot Water Heat Pump System?

Yes. Importantly, no warranty applies to the heat pump unit and the storage tank, where the chloride level exceeds 200 mg/litre and the pH is less than 6.0. If in doubt, it is recommended that water chemistry information be sought from your local council or water supplier

15. What do I do if the Sanden Eco® Plus Hot Water Heat Pump System has a problem?

Give us a call - 1300 TO PURE (1300 86 7873) - and we will help!

16. Do I need to register my warranty?

Yes.  For efficient processing of warranty claims, should they arise, please register your Sanden Eco® Plus Hot Water Heat Pump here.

17. What sizes are the Sanden Eco® Plus Hot Water Heat Pump available in?

The unit is available in four sizes as follows:
And more about the PLUS....

sandenPLUS Sizing

A heat pump is a solar energy harvesting device just like a rooftop solar electric system or old style rooftop solar hot water system. The difference is that a heatpump strips (removes) the solar energy that's in the ambient air around your home and deposits it inside the tank for you to use when required. Your Sanden heat pump hot water service gives excellent service and performance in all Australian weather conditions.

A CO2 heat pump really performs when older style rooftop solar hot water heaters don't.  Our behaviour is to use much more hot water in colder winter when it's generally much more cloudy giving little rooftop solar hot water contribution, while the Sanden's performance stays consistent throughout the seasons in Australia's temperate climate. 

The Sanden Eco Hot Water Heat pump will reduce your energy by more than 90% when compared to an average gas storage hot water service and 80% when compared to an electric hot water service.

Federal and State government subsidies are available to help make your purchase affordable and accellerate your move to a pure electric house with a renewable hot water service..  What's more - if you've got rooftop solar electric panels then you can schedule your Sanden to run during the day while your solar is producing maximising your renewable self consumption.

The Sanden is a league ahead of all the other heat pumps in the Australian market, it is part of a technology that was developed under a program lead by the Japanese government involving all the leading Japanese refrigeration companies, to build the most efficient kind of heat pump possible for the purpose of producing hot water at low temperatures.  The program was called "Ecocute" and involves using supercritical CO2 as the working fluid

The Sanden achieves more renewable energy certificates under the government's renewable energy promotion scheme than any other heat pump which is the strongest indicator of just how good a product it is.  Unlike all other heatpumps in the market the Sanden is so quiet that it's quieter than the noise in a library.

Don't waste your valuable rooftop space on an old style conventional solar hot water unit when you can put more solar electric panels in place. With conventional solar hot water in summer your system maybe losing hundreds of litres of our precious water resource daily due to overheating while a Sanden will produce just the right amount of water for your needs.

Talk to us now, for professional advice from our trained Engineers. No gimmicks, no sales tactics just straight up and down best advice and service. We offer a fully integrated service to get you off old gas or conventional electric and on a pathway to energy efficiency and renewable energy freedom.  Starting with an efficient Sanden Eco CO2 hot water service we can eliminate your annual energy usage, saving you thousands on your bills and using our know how to upgrade you to the latest most efficient solar powered lifestyle.

get a free quote