top of page

Historical Background of Heat Pump Water Heater

Air (heat pump) products have already been used in developed countries for several decades.  In the United States, Europe, Australia, China and Taiwan, heat pump products are widely sold.

Air (heat pump) water heater has unique advanced technology and system design, therefore it has a more competitive edge than ordinary gas water heater or electric water heater.

Working Principle of Air (Heat Pump) Water Heater

1. A heat pump water heater operates similarly as an air conditioner only in an opposite manner.  Air conditioner gives out hot exhaust air during the cooling process.  On contrary, a heat pump water heater draws heat energy from the atmosphere to heat water and gives off cool air. 


2. The main elements of an air (heat pump) water heater main are shown on the above diagram. The refrigerant is compressed by the compressor to achieve high temperature, then it flows into the hot water storage tank to release heat through the heat exchanger tubes.  The slightly cooled refrigerant flows back to an expansion device where it starts to evaporate and cool down rapidly.  It then flows to the evaporator and starts absorbing heat from the air, which is an endothermic effect.  Then the refrigerant is again compressed by the compressor to become high temperature and flow to the water tank, which constitute a circulation loop.


3. Air (heat pump) water heater complies with the law of conservation of energy and thermal second law.  Similar to household air conditioner, an ordinary voltage will drive the compressor running, take heat from the air through the evaporator, convey to a heat exchanger and transfer heat to the water tank. In general, unless the ambient air temperature drops below minus ten degrees Celsius (-10 ℃), a heat pump water heater will operate properly.

Comparison Between Air (Heat Pump) Water Heaters with Other Heaters

Air (Heat Pump) Water Heater Advantages


New Energy Company water heaters are elegant; safe; highly efficient; fast heating; environmental friendly; low carbon; easy to use; with large capacity and long service life for more than 15 years.


The heater can operate 24 hours around the year and can easily replace existing conventional gas or electric water heaters such that there are no more worries about the problems of old water heaters.

Air (Heat Pump) Facts

1. Air (Heat Pump) Water Heater is More Suitable for Hong Kong.


To suit Hong Kong's fast-paced life,  you need fast water heating rate.  Hong Kong consumers use higher water temperature during bath compared to other areas.  Hong Kong generally have small household flats. It is difficult to accommodate large size ordinary electric water tanks inside the flat.  Air (heat pump) water heaters have higher efficiency, faster heating, and relatively smaller water tanks. Coupled with the use of a variety of compact or split models with wall-mounted, terrace installation, etc., can result in more efficient use of home interior space.



2. How can Air (heat pump) water heater save energy.


Air (heat pump) water heater uses general household power supply instead of high voltage.  For example, a model of about 750W - 910W (about a horsepower), can produce hot water of 160 - 180L for every working cycle. It will be adequate for the use of 2 - 4 people taking shower daily and the electricity consumption is only about 2 Kwh. 


Air (heat pump) water heater can greatly reduce power consumption. Reducing consumption of 1 Kwh of electricity will lead to reduction of about 1.5 pounds of carbon dioxide normally generated by power grid.  This can reduce the damage to the ozone layer.  At the same time, air (heat pump) extracts heat from the air for water heating, and cool air is given out through the evaporator in return to the atmosphere.  This helps improving the environment and reducing the greenhouse effect.


The water tank itself has excellent heat insulation layer. Even with the compressor being idled, the water tank temperature only drops about 3 degrees a day.


Air (heat pump) water heater has fast heating rate.  Newly installed heater will take about 1-2 hours initially to heat the water from air temperature to 60 ℃.   After each use, there will be some warm water remaining inside the water tank. And the time to heat the whole tank back to 60 ℃ will be much faster.



3. Air (heat pump) water heater, though having similar compressor operation as air-conditioner, would not consume high electricity power.


Air (heat pump) water heater and air-conditioner have different mode of operation.  If the power of an air-conditioner is 1Kw, the use of electricity in one hour is 1Kwh.  Air conditioner generally works eight hours a day, and consume about 8 kWh.  The running time may be more than 8 hours in one day, and larger rooms would require higher power air-conditioners (e.g. 2Kw, or 3Kw or even higher).   The greater the power of air condiitioner, the electricity consumption will be more.

The function of a water heater is only to create enough hot water.  For example, a 4-person household will use about 300 liters of hot water daily. The heater needs to run for about 1.5 hours daily, which is only 1.5 kWh to produce such heat.  So though they are using the same compressor principle, their operation time vary greatly, so electricity consumption are not similar.



4. During winter cold weather, air (heat pump) water heater can still draw heat energy from air.

Heat pump system uses refrigerant as media.  Refrigerant evaporation temperature can be minus twenty degrees Celsius (-20 ℃).  There will be some temperature difference between the refrigerant and the surrounding air.  So during winter in Hong Kong, the refrigerant inside the evaporator will still be vaporized and continue to absorb heat from the air.  The warm refrigerant will pass through the compressor to further heat up and transfer the heat to the water tank.

Indeed, the normal operation  temperature of heat pump is in the range of -7 ℃ and 43 ℃.  Even the outside air is close to zero degree Celsius, the air is relatively warmer than the refrigerant though the heat energy is low. In general the temperature in Hong Kong winter is between to 10 ℃ to 15 ℃ and the heater will still be operated as normal and produce adequate hot water.



5. Air (heat pump) water heater can reduce carbon dioxide emissions.


If a family replaces a conventional electric water heater with an air (heat pump) heater, there will be a 62% reduction of households total carbon dioxide emissions used on producing hot water.  If one-fourth of the world's families choose air (heat pump) water heaters to replace ordinary electric water heaters, we can have a reduction of more than 4 billion pounds of carbon dioxide annual emissions from the power grid, equivalent to more than 360,000 vehicles per year total emissions.



6. Air (heat pump) water heater can be used together with other gas or electric water heaters.

Typically, a properly designed air (heat pump) heater will be sufficient for home use. It is not necessary to add extra gas or electric water heater.  But if the user do not wish to discard the existing old water heaters, they can be maintained as backup equipment and be used for unexpected special circumstances, for example, in a very cold day the number of overnight guests have suddenly increased.

bottom of page