Electric Heat Pump Water Heaters
Review and Buying Tips

Selection of the best electric heat pump water heaters - review and buying tips. Who should purchase a heat pump for water heating - HPWH? Find out how these electric water heaters, also known as hybrids, can be Energy Star compliant and perform with energy efficiency at least twice as high as the conventional tank heaters.


  1. Benefits
  2. Main components
  3. How does it work
  4. Selecting tips
  5. Heat pump vs. electric tank-type
  6. Heat pump vs. gas tank-type
  7. Popular models
  8. Advantages & disadvantages

Benefits of heat pumps

Heating water with the electric heat pump water heaters is very efficient and economical, where the Energy Star compliance brings more savings either from the utility companies or a government (when applicable).

According to energystar.gov, annual energy costs for the tank-type electric water heater and family of four is a little over $600, while for the heat pumps close to $300.

Heat pumps with the Energy Star certification can save over $3400 over their lifetime for a family of four.

The heat pumps use a straightforward process of extracting the heat from the air and pass it to water. Since they are not generating the heat but moving it from one place to another, the energy factor (EF) and first-hour rating are significantly higher than the EF found on conventional water tank heaters.

They are also known as eco-friendly hybrid water heaters since they combine two technologies; heat pumps and electric heating elements. Hybrid technology allows either individual or combined operation of both electrical heating elements and the heat pump.

Components that make a heat pump unique

Rheem heat pumpRheem hybrid

Heat pump water heaters are similar to electric tank-type heaters. They have a storage tank to store hot water and insulation to keep heat inside the unit for a longer period of time. The submerged anode rod protects the metal tank from corrosion. At the bottom, there is a drain valve for easier maintenance and flushing, and close to the top TPR valve is used as a safety element to protect the unit from extreme pressure and temperature.

Two heating elements with thermostats are there for supplemental water heating and temperature adjustment when the heat pump operates with low efficiency, which happens during cold weather.

Now, the difference is found inside and on top of the water heater, where several components such as fan, compressor, evaporator, and condenser are making this technology unique.

Models such as Rheem, AO Smith, or GE utilize advanced monitoring with an electric circuit board and LED control panel using touchpad buttons so you can easily change the temperature or efficiency setting, for example.

How does the heat pump work?

The fan located at the top of the water heater forces the warm room air across the evaporator coils where the liquid refrigerant vaporizes. The compressor increases the pressure and temperature of the gas/refrigerant, which goes through the condenser, turns back into liquid, and exchanges the heat with the surrounding water. This is how this electric water heater increases its efficiency by over 200%. While it heats the water, the unit cools and dehumidifies the surrounding air as well.

Selecting tips and factors to consider

The following elements are what you should consider when choosing the best hybrid water heater for your home:

Capacity. It is important to consider the size of the house, how many bathrooms there are, and the size of the family. Usually, for households with four members, a 50-gal unit is sufficient but depends on the first-hour rating and recovery rate. They are mostly available in sizes from 50 to 80 gallons.

Type. While this buying guide is for stand-alone or integrated models, you can still buy and install an add-on to an existing electric model.

Efficiency. If you want to save more, choose the heater with the highest energy factor.

Climate. Colder weather directly affects the efficiency of the heat pump. During those days, the electric elements are the main source of heating.

Location. Make sure that the room for the heat pump installation is big enough for normal air circulation, servicing, and maintenance. Keep in mind that hybrids require at least 1000 cubic feet of space. It can use the outside or surrounding indoor air. These tips might help you when installing a heat pump.

Brand. Choose the model from a reputable manufacturer, such as Rheem, AO Smith, Bosch, Stiebel Eltron… Make sure to contact the certified installers for the installation and safe work so the manufacturer doesn’t void the warranty.

Warranty. The best models with a lifetime warranty include the storage tanks made of stainless steel, making them resistant to corrosion.

Heat pump vs. electric tank-type

  • Heat pumps/hybrids are 2-3 times more efficient than the electric tank-type.
  • Hybrids rely on heat pump technology and electric heating elements as the backup. Electric models use only heating elements.
  • Hybrids are slow in producing the heat, but since they mostly have four operating modes, the recovery rate and efficiency vary.
  • Hybrids cost much more than electric. The 50-gal unit can easily cost over $1000, while the electric few hundred bucks only.
  • Hybrids are more advanced.

You can get more information about heat pumps vs. electric water heaters in this article.

Heat pumps vs. gas

  • Heat pumps are even more efficient than gas tank-type, whose efficiency can go as high as 70% (conventional type). This means more money in your pocket over the years.
  • The recovery rate is much higher on the gas type.
  • The gas type heats water fast.
  • Gas models are cheaper.
  • Gas type can work even during the power outage or cold weather.
  • Heat pumps use advanced electronics; some have WiFi capability, usually come with a large LCD and at least four operating modes for enhanced comfort, flexibility, and convenience, while maximizing energy savings.

Where to use heat pumps

The best location for installation is a room with a higher temperature, such as the attic or the utility room, where the furnace is installed. It is recommended for regions with a warm climate, such as the southern part of the US, or where the average temperature is between 40 F and 90 F. The efficiency increases when the temperature of the surrounding air goes up.

If used in colder areas, it must be installed indoors where the heating is supplemented with the heating elements. It is an excellent choice for new homes, or as the replacement for your old electric water heater, in the basement, garage, or attic.

Popular models

Most of the manufacturers of HVAC equipment are making hybrid water heaters that can be different in what they offer. Below are the most popular:

Rheem heat pump PROPH50

Rheem heat pump PROPH50 is the 50-gal hybrid water heater that is coming with ultra-high energy efficiency. According to the Rheem manufacturer, this unit can save more than $4000 in lifetime energy costs, and it pays for itself in less than two years. According to the specs., the energy factor is 2.45 while Uniform Energy Factor (UEF) is 3.70, which is almost three times more than standard electric, or even more when compared to gas type. This allows Energy Star compliance for the unit.

For homes where more hot water is needed, the fact that the first-hour rating is 67 GPH might be helpful while selecting the right unit. Also, with the operating temperatures, which are in the range from 37 F to 145 F, you will be able to utilize the unit more days in a year, even in colder climates.

For convenience, enhanced comfort, and additional savings, Rheem PROPH50 offers several operating modes, also providing more flexibility to users.

Rheem exclusive EcoNetConnect allows Wi-Fi connection, and by using the available mobile app, users can quickly get full control of the system remotely.

Moreover, the advanced electronics, diagnostics, control, and monitoring allows great flexibility and convenience for users.

The unit comes with an extended 10-year warranty.

AO Smith Voltex HPTU-50N

AO Smith Voltex HPTU-50N is another great 50-gal hybrid water heater that is designed to heat the water and, at the same time, dehumidify and cool the ambient air. Like the above Rheem heat pumps, Voltex also comes with a 10-year warranty and a high first-hour rating of 66 GPH.

Using one of the four operating modes, the user can set the unit to work with the highest efficiency, which is 3.42, to get the fastest recovery or just put it in vacation mode for savings and protection from bacteria development or freezing when away. As the above Rheem, Voltex is equipped with the two heating elements that have dry-fire protection, sacrificial but heavy-duty anode rod that ensures better corrosion protection and longer life, and advanced electronics with the LCD.

GE GeoSpring

GE GeoSpring hybrid water heater GEH50DFEJSR uses both heat pump and electric technology for efficient water heating. It uses the same connections for fast and easy installation. It is similar to the electric unit, almost the same footprint, but is more advanced; offering a cool control panel with the back-lit LCD, buttons to set the temperature, and choose the operating mode.

Stiebel Eltron Accelera 220 E

What makes Stiebel Eltron Accelera 220 E different from the rest in this review is that this unit is not a hybrid, as explained by the manufacturer – the unit utilizes only the heat pump technology and doesn’t have heating elements as the backup. The reason is that they wanted to offer the most efficient option, so the unit doesn’t have to choose between different settings. In the case of the ultra-high demand for hot water, the Accelera can use the single booster element located at the top of the unit.

The unit doesn’t have the “vacation” mode when the user is away, and which is used to protect the unit from energy waste and freezing during wintertime, while it relies on its super thick insulation. The energy factor is 3.05 (Energy Star), and the first-hour rating is 50.3 GPH.

As opposed to other heat pumps, which are equipped with heavy-duty anodes but still sacrificial, the Accelera comes with the electronic anode, which allows maintenance-free protection.

The smallest model comes with 58 gallons but is advertised as the 50-gal model.

Advantages of heat pumps

  • By installing a heat pump, instead of conventional electric, the electric bills will be reduced by several hundred dollars annually.
  • Frequent incentives decrease the initial purchase and installation price.
  • The advanced control allows accuracy, savings, convenience, and enhanced comfort.
  • Wi-Fi capability for remote control and monitoring.
  • Advanced diagnostics for easier troubleshooting.

Disadvantages of heat pumps

  • Expensive if there are no incentives.
  • Need supplemental heat if installed in cold areas.
  • It needs a sufficient air supply for the proper work.
  • Loud. The heat pump often makes a humming noise, similar to AC, which doesn’t make it suitable for installation close to the bedrooms.


Electric heat pumps for water heating are expensive but an excellent long-term investment due to their superior efficiency and Energy Star compliance, making them eligible for tax breaks and other rebates. They are recommended for high demanding homes due to the high recovery rate and cost reduction of up to 80% on some models.

Whether you are planning to reduce the cost or environmental impact, a heat pump water heater is a great choice. Due to its construction, they can easily replace the electric type and in some regions without the need for supplemental heating. Also, with the significant incentives offered by utility companies or the government, the cost of purchasing and installing heat pumps can be very affordable, even on par with the standard electric model.

Various types of heat pumps such as air-to-air, water-sourced, and others can be found on this website heatpumpshq.com.


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