HPWH (Heat Pump Water Heater) Technology


Heat pump water heaters work by drawing heat from the environment and transferring that heat through a compressor into a water tank. Similar as air conditioner, it works through 4 main components which are Evaporator, Compressor, Condenser and Expansion Valve. Its lifespan can be up to 15 years.

Heat pump water heater is highly energy efficient as most of the energy for heating comes from the external environment, and only a fraction comes from electricity. For every KW of electricity consumed the heat transferred will be 4 times as much as initial input.

The amount of electrical energy needed to heat water is greatly reduced compared to a conventional electric water heater in which, for every KW of electricity consumed the heat transferred is only 0.95KW.

Therefore, the COP (Coefficient of Performance, ratio of output power to input power) of heat pump water heaters can be as high as 5.

Working Principle

  • The operation begins with air being forced through an evaporator which contains a liquid refrigerant, with the help of a fan.
  • This refrigerant evaporates to a gas and extracts heat from the ambient air.
  • The warm gaseous refrigerant then passes through the compressor, which increases its pressure and it becomes a hot gas.
  • This hot gas enters a heat exchanger (condenser) and transfers its heat to the water flowing from a storage tank.
  • The refrigerant cools down in the condenser and becomes a warm liquid.
  • It then passes through an expansion valve and becomes a cool liquid and enters the evaporator.
  • Thus heat absorbed from the air is transferred to the water and the heating continues till the desired temperature is reached.
  • The cycle is then repeated in this manner.