Electric heat pump water heater is the ultra-efficient unit that uses two technologies for water heating, in high-demanding residential homes and for commercial applications. Explore the main features of the heat pumps, benefits, the most popular manufacturers and review the specs side by side.
Electric heat pump water heater (HPWH) is designed to draw heat from the surrounding air and transfers the extracted heat to water.
It actually moves the heat from one place to another, rather that heating the water directly. It works similar as refrigerators or air conditioners, in reverse.
Electric heat pump water heater uses the principles of refrigeration to draw the heat from air by using the built-in fan, refrigerant, evaporator coil and compressor.
The heat from air causes the refrigerant to vaporize, which goes to the compressor where the refrigerant fluid further increases its temperature. The hot vapor from the refrigerant enters the condenser coil where it transfers its energy to the cooler surrounding water in the heat exchanger and further in the storage tank.
In addition to water heating, the surrounding air is cooled and dehumidified. This is another benefit to heat pump's owners, as the cooled air can be used for cooling houses and therefore reducing energy consumption.
Cold water inlet
Hot water outlet
Upper and lower thermostat
There are few types of heat pumps available for you to buy:
An integral electric heat pump water heater comes as one package and features the pump connected to the storage tank with the back-up resistance heating elements. It has the same footprint and connections as the standard storage tank, and installation is similar, except requirements for the condensate drainage.
Add-on water heater heat pump, or retrofit unit, is installed in conjunction with an existing heater, either on the top of the tank or wall-mounted. It replaces the function of the tank's lower heating element, being the main heat source. Small pump has to be installed between the tank and the pump to circulate the water.
There is also a geothermal heat pump that uses the energy from ground during the winter and is used mainly for home heating. By adding a small heat exchanger, called desuperheater you can heat water as well.
Heat pumps do not generate energy directly, and while they operate, they tend to cool the space they are in. This is the reason why the best spots for installation of heat pumps are isolated locations. These include garages, attics, technical rooms, basements, and rooms where the average temperature is between 40 F and 90 F year-round, with the sufficient air.
In colder climates they will be installed indoors and would provide cooling and dehumidification inside the room where it is located.
There is a tendency in colder areas that the ice builds up on the condensing coil. This is what causes restrictions in air flow and damage in the internal components. Recommendation is to buy a pump with the "Defrost Mode" so you will never experience such operation problems.
You should consider installing a heat pump water heater if your home is a high-demand home and where the electricity and gas rates are high and gas is not available.
When it comes to the efficiency and money savings, heat pumps are better solution for heating the pool than the gas water heaters. It is also easy to install, it is reliable and efficient.
As mentioned before, the HPWH provides an energy saving alternative to the electric heaters because less energy is needed to move heat than to create it.
Electric heat pump water heaters are the only electric heaters that qualify for a tax credit. In order to qualify, the pump has to have an energy factor, EF, at least 2.0 and minimum first hour rating of 50 gph. Look for the Energy Star label and you will be able to save up to 30% of the cost or up to $1,500 with the included installation and labor costs.
Electric heat pump water heater has more than twice the efficiency of conventional electric water heaters, and performs the best in warm climates while it cools and dehumidifies the surrounding air.
The efficiency depends on the surrounding air, incoming water temperature, heat transfer characteristics of the unit and losses within the system.
When buying the electric heat pump water heater use three parameters for comparison:
The heating coefficient of performance, COP, is used for the performance, and it defines the ratio of the energy of heat pump to the electrical energy unit.
Energy Factor or EF is the ratio of energy output to energy input. An average value for these pumps is between 2 and 2.5 (for reference; maximum EF for electric heater is close to 1).
The First Hour Rating (FHR).
Our recommendation is to look at the Rheem manufacturer as it produces units with the ultra-efficient heat exchanger made of Titanium. Specially designed heat exchanger helps in the reduction of deposit build-up also.
The GeoSpring electric heat pump water heater from GE as the Energy Star unit is also a good pick, featuring multiple settings including high demand and hybrid mode, electronic back-lit LCD display, flexible and easy-to-use electronic control panel.
Here is the comparison chart of the popular models:
Other popular heat pump manufacturers are: AirGenerate, Stiebel Eltron Accelera 300, E Tech by AO Smith, North Road Technologies, Sanyo, Hitachi, Toshiba...
The main problem with the heat pump water heaters is the initial high purchase and installation costs, but these can be offset it by its significant reduction in energy consumption. These products are good investment as they reduce the heating costs by as much as 50% while offering the "green" technology with the reduced impact on the environment.
The picture is courtesy of energysavers.gov