A heat pump water heater (HPWH) operates on an electrically driven vapor-compression cycle and
pumps energy from the air in its surroundings to water in a storage tank, thus raising the temperature of
the water. HPWHs are a promising technology in both residential and commercial applications due to
both improved efficiency and air conditioning benefits.
Residential HPWH units have been available for more than 20 years, but have experienced limited
success in the marketplace. Commercial-scale HPWHs are also a very promising technology, while their
present market share is extremely low.
This study dealt with reviewing HPWH systems in terms of energetic and exergetic aspects. In this
context, HPWH technology along with its historical development was briefly given first. Next, a
comprehensive review of studies conducted on them were classified and presented in tables. HPWHs
were then modeled for performance evaluation purposes by using energy and exergy analysis methods.
Finally, the results obtained were discussed. It is expected that this comprehensive review will be very
beneficial to everyone involved or interested in the energetic and exergetic design, simulation, analysis,
performance assessment and applications of various types of HPWH systems.