Heat Pump Water Heater

Basic components of a heat pump:

The evaporator draws the surrounding air over the evaporator fins, the cold fluid circulating inside the evaporator extracts heat from air and gets vapourised and moves in to the compressor where the vapour is subjected to high pressure and high temperature. The cold water from the storage tank is made to circulate through a condenser, where the vapour which is of high temperature and under pressure transfers the heat to the cold water. The water gets heated and moves back into the storage tank. The vapour loses heat and condenses into a liquid. The condensed liquid is made to expand in an expansion valve, which lowers the temperature and pressure, and this cold liquid moves in to evaporator and is now ready to extract heat from the warm air and this cycle is repeated.

The heat pump automatically switches off when the temperature in the storage tank reaches the desired value. As the heat pump takes the heat from the surrounding area, its ability to extract heat from the air depends upon the heat content in the air. Therefore, in warm areas and during summer, the heat pump operates at higher efficiency and in colder months, the heat pump will operate at a slightly lesser efficiency. The heat pump efficiency is measured in a unit called "COP" (co-efficient of performance). A typical heat pump's COP would be between 2.5 - 4 depending upon the season and other factors.