Traditionally heat pumps were used for space conditioning. In modern times heat pumps are used for electric heating of water. Water to water heat pumps work three times more efficiently than electric resistant water heaters. The heat pumps can discharge the same amount of hot water with only one third amount of electricity used.

Water to water heat pump water heaters move the heat in to the water from the external environmental surroundings. The heat pump is provided with electric heating elements inside the water tank when the demand increases rapidly. Water heat pump water heaters can be bought as integral units along with storage tanks. The can be additionally combined with the electric resistant water heaters. They prove to be highly expensive and prove to be an excellent alternative for electricity. Heat pump water heaters have the capacity to save up to 45 % of the water heating cost.   

Water to water heat pumps do not produce or generate heat. On the other hand the heat pumps gain more energy. There are two or three EF's in the water heat pumps.  The air that is surrounding the unit gets cooled or de humidified when the water heat pumps moves the heat inside the water. Production of about 1/2 ton air is extremely helpful when the house requires cooling. During the winter season the cool air might increase the demand on the system.  

Water to water heat pumps must be specially designed and technical experts who are qualified in this field should do the installation process. Single or one piece systems need less of designing work and are easier to install. Contractors must be selected with caution.

Water to water heat pumps water heaters must be necessarily installed within the house as they have the tendency to freeze if there is a drop in the temperature below 45 degrees. Water heaters should not be confined to particular space since they require air for the extraction of heat. The maintenance of water heater pumps is high as compared to the other systems. The coils of heat exchanger should be cleaned regularly depending upon the quality of the water. The heating process is slow in water heat pumps. Some of the electric resistant water can heat up to a maximum of 20 gallons within an hour. Storage tanks with bigger capacity will be helpful in avoiding scarcity of hot water.